wilds by the indefatigable editor. The remarkable accession to the North American Flora which this Catalogue records is that of Littorella lacustris.

A. G.

3. The Native Flowers and Ferns of the United States, edited by Professor Meehan and chromo-lithographed by Prang & Co., evinces its life and good promise of success in the prompt appearing of Parts 3, 4, and 5. Our notice of the first parts is so recent and particular that we need only announce the new ones, which maintain the general character. Botanists may thank the editor for interspersing some figures of plants which the florist and common observer would pass by unnoticed, such as Carex stricta, Cuphea viscosissima, and Pedicularis Canadensis.

A. G.

4. Zoological Distribution, and some of its Difficulties; by P. L. SCLATER, Esq., M.A., Ph.D., F.R.S.-After pointing out that "locality" is quite as much a part of the proper characters of natural groups of animals as form and structure, the lecturer spoke of "specific" and "generic" areas, and of the doctrine of their continuity. He then treated of "representative species," and showed that, while insular representative species are usually distinct, continental representative species are not unfrequently found to be connected together by intermediate forms. The only hypothesis that would explain these and other phenomena of "distribution" was that of the derivative origin of species. But the question was, were there not exceptional cases of distribution which threw difficulties in the way of the universal adoption of this hypothesis? It must be admitted by all who had studied distribution in any group of animals that there were many such difficult cases. The lecturer then proceeded to call attention to six cases of abnormal distribution in the classes of mammals, birds and reptiles, namely:

(1.) The Little Blue Magpie of Spain.-The general character of the birds of Spain did not differ materially from that of the rest of Southern Europe, although a few North African species intruded into its limits. One little bird only seemed to have been introduced from afar, and disturbed the general uniformity. The little blue magpie of Spain (Cyanopica Cooki) had not only no near relatives in the rest of Europe, but we must go to the farthest part of Siberia and Northern China before we met with its true allies. Here was found the Cyanopica cyanea, so closely allied to the Spanish bird as to be barely distinguishable. This was, therefore, an undoubted instance of a discontinuous generic, if not specific, area, and in order to bring it within ordinary rules it was necessary to suppose that the parent-form had been formerly existent throughout Europe and Central Asia, but had for some reason become extinct in those countries.

(2.) Oxyrhamphus and Neomorphus.-These two South American genera of birds offered somewhat parallel cases of broken distribution. Of the peculiar Passerine form Oxyrhamphus, only two very closely allied species were known, one (O. flummiceps) in Southeastern Brazil, and the other (0. frater) in Central

America, the genus being quite unrepresented in the intermediate countries. In the Cuculine genus Neomorphus, the Central American form (N. Salvini) was again very nearly similar to the Brazilian (N. Geoffroyi), whereas in the intermediate countries three other quite distinct species were known to occur.

(3.) Pitta Angolensis.-Not less than from thirty to forty species of the brilliantly colored birds of the genus Pitta were known to science, distributed from India, on the north, through the great Asiatic islands into Northern Australia. But one single Pitta, in every way typical in structure, and closely allied to an Indian species, occurred in a limited district of Western Africa, the genus being quite unknown in intermediate localities. This was a clear instance of a discontinuous generic area.

(4.) The Solenodon of the Antilles.-The insectivorous mammals, according to the best authorities, constituted ten different families, which were mostly restricted to the Palearctic, Indian and Ethiopian regions, and were entirely unrepresented in Australia and South America. Two families only extended into the northern portion of the New World, the moles (Talpida) and the shrews (Sorecida). But there was one very exceptional case. The genus Solenodon, two species of which were known from two islands in the West Indies, belonged not to the shrews or moles, but to the family Centetido, otherwise entirely confined to Madagascar. If, therefore, the descent of Solenodon and Centetes from a common ancestor were assumed, the following assumptions must also be made. First, that the West India Islands had been united by land to Africa; and secondly, that the Centetida bad formerly extended all through Africa, where there were now no traces of them.

(5.) The Distribution of Lemurs.-Recalling Solenodon to our minds, we might well have expected that the Lemurs, one of the most prevalent and characteristic mammal groups of Madagascar, would have had allies in America, but such was not the case. The only members of this group not found in Madagascar were met with in Africa and parts of the Indian region. It was therefore manifest that, assuming the origin of the Lemurs from a common source, a continent must have formerly existed in the Indian Ocean, and formed the ancient home of the Lemurine family, of which the fragments were now so widely sundered. It would, however, be difficult to reconcile this hypothesis with that of the former land-connection of Madagascar with the Antilles through Africa, previously adverted to.

(6.) The Giant Land Tortoises. The giant land tortoises, which had lately formed the subject of the elaborate studies of Dr. Günther, presented a still more extraordinary instance of anomalous distribution. These animals now only existed in the Galapagos Islands and on the coral reef of Aldabra, northwest of Madagascar, but a third group, which formerly inhabited the Mascarene Islands, had only recently become extinct. In order to derive these three groups of allied species from the same stock, it

would be necessary to assume first that giant land tortoises were formerly distributed all over South America and Africa, where no traces of them now existed; secondly, to suppose that the Galapagos were formerly united to America; and thirdly, that the Aldabra reef had once formed part of land that was joined to the African coast. But even then all the difficulties would not have been surmounted, for it appeared that the Mascarene form of these tortoises was more nearly allied to that of the Galapagos than to that of Aldabra. It would further have to be assumed therefore, in order to bring these facts into harmony with the usual theory, that the Mascarene Islands had remained united to the African coast after the Aldabra reef had been separated from it.

.

These six cases were only selected instances of the many difficulties met with in endeavoring to account for all the known facts of distribution by the hypothesis of the derivative origin of species. It would be easy for those who had studied distribution in any group of animals to add to them almost indefinitely. Two other more general phenomena of distribution, which it appeared to be difficult to reconcile with the derivative hypothesis, were also briefly adverted to, these were the existence of "tropicopolitan" forms, that is, of forms common to the tropics of both hemispheres, and the presence of several closely allied species in the same area. In the first case, it was difficult to understand where the continent could have formerly existed which afforded a home to the ancestors of the similar species now so widely separated. In the second place, it never appeared to have been explained satisfactorily how more than one form could have succeeded to a pre-existing one in the same area, and the hypothesis that allied forms had always originated in separate areas, and had come together into the same area by immigration, appeared, in some cases to be almost untenable.

These and other minor difficulties had led the author rather to question whether identity of structure must be taken, without exception, as an indication of immediate descent from a common parentage. At any rate, the subject seemed to be one still open for discussion, and not, as some recent writers had appeared to assume, a matter which must be regarded as fully and incontrovertibly set at rest.—Royal Institution, Feb. 1878.

5. Corals of the Atlantic.-G. Lindström has described and figured several new corals from the Atlantic bed, in a paper in the Transactions of the Swedish Academy, vol. xiv, 1877.

IV. MISCELLANEOUS SCIENTIFIC INTELLIGENCE.

1. Transactions of the Connecticut Academy of Arts and Sciences, Vol. III, Part 2.-This part closes the volume. It contains a paper by S. F. Clark, on the Hydroids of the Pacific Coast south of Vancouver Island; by F. M. Turnbull, on the anatomy and habits of Nereis virens; by J. K. Thacher, on Median and Paired Fins, a contribution to the history of verte

brate limbs; by S. I. Smith, on the early stages of Hippa talpoida; by J. Willard Gibbs, on the equilibrium of heterogeneous substances, this last paper occupying 220 pages of the number.

Mr. Thacher closes his excellent paper-the second on vertebrate limbs-with the following addendum.

Since the views expressed in the foregoing pages were complete in my own mind six or eight months ago, I had looked for confirmation of them in the brilliant investigations of Balfour on the development of Elasmobranchs. The preliminary account, however, in the Journal of Microscopical Science, contained nothing bearing on the point, and the papers in the Journal of Anatomy and Physiology I have been able to obtain only irregularly. Immediately after the last proof of the preceding pages had been received, the number of that Journal for October, 1876, came into my hands. Here Balfour devotes three or four pages to the limbs. He says: "If the account just given of the development of the limb is an accurate record of what really takes place, it is not possible to deny that some light is thrown by it upon the first origin of the vertebrate limbs. The fact can only bear one interpretation, viz: that the limbs are the remnants of continuous lateral fins."

"The development of the limbs is almost identically similar to that of the dorsal fins." He goes on to state that while none of his researches throw any light on the nature of the skeletal parts of the limb, they certainly lend no support to Gegenbaur's view of their derivation from the branchial skeleton. Thus these results have not only been reached independently, but from two different classes of facts. To the belief in the original continuity of the lateral fins and the homodynamism of median and paired fins I was led by observations on adult forms, and particularly on the skeleton. Balfour comes to the same results from embryological investigations, in that group from which on general grounds an answer was most to be expected; nor do these investigations regard the skeleton.

I have also just received the last number of the Morph. Jahrb. It contains a paper by Wiedersheim* confirming Gegenbaur's view respecting the double nature of the centrale. This had previously been shown only in the tarsus of Cryptobranchus Japonicus (and in the Enaliosaurs). Wiedersheim shows its double character in three Siberian species of Urodela, in both carpus and tarsus. This is a very important confirmation of the chiropterygium, and relieves us of suspicions with regard to its correctness when we push our inquiries into earlier history and more simple forms.

In the same number of the Jahrbuch is a paper by Gegenbaurt on the archipterygium theory. He modifies his explanation of the Stapediferal limb to accord with Huxley's view of the homol

* Morph. Jahrb., Bd. ii. IIft. 3. R. Wiedersheim, Die ältesten Formen des Carpus und Tarsus der heutigen Amphibien.

+C. Gegenbaur, Zur Morphologie der Gliedmaassen der Wirbelthiere.

ogy of edges and faces of limb and fin. He says that while he does not think the correctness of this view fully demonstrated, still he thinks there is a decided balance of probability in its favor. Therefore the ulnar side of the arm now appears as the Stammreihe. In other particulars Gegenbaur reaffirms his previous views. He proceeds to devote considerable space to the discussion of the origin of the archipterygium, and again proposes to assimilate the limb and limb-girdles to the gill-arches with their rays. He supports this suggestion with considerable argumentation. To this position the archipterygium theory leads him.

2. National Microscopical Congress. By invitation of the Indianapolis Lyceum of Natural History and the coöperation of other societies a call has been sent out for the meeting of Microscopists at Indianapolis in August, to be continued for not more than a week, and to commence on the 14th of that month. The Governor and other State officers, and the Mayor and citizens of the place, have united in offers of hospitality to the convention; and fare at reduced rates can be obtained by members at the best hotels ($2.00 at the Bates House, Grand Hotel and Occidental Hotel, $1.75 at the Remy Hotel). Those who may attend the convention are desired to bring scientific communications, instruments, objects for the microscope, and whatever pertains thereto that will instruct their fellow-workers with the microscope." Letters should be addressed to W. WEBSTER BUTTERFIELD, M.D., Secretary of the Committee of Arrangements. The daily sessions will be held in Hall Nos. 52, 54, 56 and 58 of the Court House. The time for the Congress is one week before the meeting of the American Association at St. Louis.

66

3. Geographical Surveys west of the 100th Meridian, in charge of First Lieut. G. M. WHEELER, under the direction of Brig. Gen. A. A. Humphreys, Chief of Engineers, U. S. A. Vol. II. Astronomy and Barometric Hypsometry. 572 pp. 4to. Washington, 1877.-This volume from the Wheeler Expedition under the War Department, consists in Part I of special Astronomical Reports, and in Part II of a Report on Barometric IIypsometry. The first comprises numerous tables of observations made for the purpose of time, latitude and longitude determinations, at various places in Utah, Wyoming, Montana, Colorado, New Mexico, Nevada and Nebraska, together with the geographical positions arrived at and other particulars connected therewith, and is illustrated by map sketches of the principal places and stations, and a plan of the Observatory at Ogden, Utah. The authors connected with these reports are Dr. F. Kampff, J. H. Clark, W. W. Maryatt, Professor T. H. Safford, W. A. Rogers.

The results of barometric hypsometry are from observations made in the years 1871 to 1875 included, and reported by First Lieut. W. L. Marshall, Corps of Engineers, U. S. A. The instruments are described, the methods of observing, and tables of altitudes are given. The report also contains tables of hourly observations of barometric, thermometric and hygrometric and other phenomena