the malar bone formed part of the continuity of the zygomatic arch, correcting the statement of Dr. Coues in his "Monograph of American Rodentia," page 253, with regard to the jugal of the muskrat, which is there described as "a mere splint, not forming by itself any part of the continuity of the arch, for the squamosal and maxillary spurs are absolutely in contact. This is a strong point of Fiber." Mr. Scudder remarked that muskrats were able to live four to six minutes under water, owing probably to the enlargement of the abdominal aorta. He believed muskrats to be omnivorous, and said that the same individual could be taken repeatedly in the same trap.

Dr. R. W. Shufeldt made a communication UPON THE PRESENCE OF RIBS ATTACHED TO THE OCCIPITAL BONE OF THE BLACK BASS, MICROPTERUS SALMOIDES.* He remarked, in the course of his description, that he had recently made quite a number of dissections of this fish, and in every instance had found a pair of ribs upon the occipital bone, just above and internal to the foramen of the vagus nerve. They are without epipleural appendages, but otherwise like the abdominal ribs. If this fact be new to science, it is a very interesting discovery of great morphological significance, and introduced an important factor in the theory of the segmentation of the skull. It had not been noticed in any of the prominent works upon comparative anatomy generally used as text-books, nor in a recent and very thorough article by Dr. Sagemehl upon the cranial osteology of Amia calva (Morph. Jahrb., Vol. 9, pt. 2, 1883). Dr. Shufeldt had also discovered these ribs, thoroughly developed, in the tunny, Orcynus thynnus, and thought that they would doubtless be found in others of the Scombride and Centrarchide.

SIXTY-FOURTH MEETING, May 17, 1884.

Prof. C. V. Riley, Vice-President, occupied the chair. Thirtyfive members were present.

Dr. J. M. Flint, in a paper on CHINESE MEDICINES, after giving

* 1884. SHUFELDT, R. W. Osteology of the Large-mouthed Black Bass «Mi ropterus salmoides). <Science, III, p. 532, 1884.

5*

a brief account of the history of medicine among the Chinese, according to their own authors, discussed their theories in regard to the nature and causes of disease and the action of remedies. Their ignorance of anatomy and the consequent effects upon their theory and practice was shown. The materia medica of the Chinese was then considered in detail, its peculiarities, as well as its resemblances to our own, present and past, as illustrated by the collections of Chinese drugs now in the possession of the U. S. National Mu

seum.

A paper by Mr. Wiley Britton on the BUFFALO GNAT OF TENNESSEE was read, in which the author stated that its habitat, in his opinion, was confined to the Mississippi Valley, below the mouth of the Ohio river. It generally makes its appearance about the first of April, and remains from two to four weeks; it destroys annually considerable numbers of live-stock, particularly mules and horses, which, however, could be protected by thorough greasing. The bite of this gnat is poisonous, causing a swelling somewhat like a bee sting. Prof. C. V. Riley stated that this gnat is a species of Simulium.

Dr. Bean read a paper entitled THE WHITE FISHES OF NORTH AMERICA. The speaker said there were twelve species indigenous to North America, besides the "Inconnu," which is not properly a white-fish, though related to it. He introduced into the list Coregonus lavaretus, the German "Maræna." He made a few general remarks concerning the wide distribution, great abundance, and importance of the white fishes as food, and stated the range of each species, its maximum size and weight, and its variations through age and conditions of habitat. A brief key to the species, intended to facilitate their speedy identification, and based upon natural characters only, was included in the paper.

Dr. Thomas Taylor exhibited a new micrometer of his own invention for measuring accurately and instantly to the 1-2000 inch the thickness of any object. In a second communication he stated that Pseudo Bacteria were produced by the heating of blood at a comparatively low temperature, and proposed to make experiments for the purpose of deciding whether a continuous fever of four or

* 1884. BEAN, TARLETON H. The White Fishes of North America. Trans. Amer. Fish Cultural Association, 13th meeting, 1884, pp. 32-39.

five days with the blood at 104° F. would produce the same results as blood artificially heated to 110° F. If so, it would account for mistakes that have been made by persons inexperienced in examining the blood of fever patients, who reported the presence of Bacteria, or broken blood corpuscles, as shown by Beal and others. Dr. Taylor also explained a method of obtaining upon a screen an apparent image of a microscopic object, by placing the microscope horizontally and at right angles to the screen. While looking through the microscope with one eye, the other is directed toward the screen, upon which an image becomes apparent, its magnification depending upon the distance of the observer from the screen.

SIXTY-FIFTH MEETING, May 31, 1884.

The President occupied the chair. Thirty members were pres

ent.

Prof. L. F. Ward, Chairman of the Committee on Cultivated Plants growing in the District of Columbia, submitted a report of progress.

Mr. James E. Benedict made REMARKS ON THE RECENT CRUISE OF THE STEAMER "ALBATROSS" IN THE GULF OF MEXICO AND the CARIBBEAN SEA, describing the events of the voyage, and exhibiting some of the most remarkable objects collected.

Ensign E. E. Hayden, U. S. N., presented, through Prof. Ward, a paper on A NEW METHOD OF FIGURING FOSSIL LEAVES AND OTHER OBJECTS BY THE AID OF PHOTOGRAPHY,* remarking that a saving of time and increase of accuracy was thereby attained. The method consisted in drawing with India ink upon a silver print photograph the outline of the object to be figured, the defects of the photograph being supplied by the draughtsman through comparison with the specimen. The photograph is then dismissed, and a photoengraving is made from the black lines of the sketch which remains.

In the discussion which followed, it was shown that this process was novel in its successful application by the author to engrave fossil leaves.

Mr. J. A. Ryder read a paper on THE DEVELOPMENT OF VIVIPA

ROUS MINNOWS.* The species under discussion was the form known as Gambusia patruelis, B. & G The points which were especially alluded to were the following: The fact that the young fish developed within the body of the female parent and within the follicles in which the eggs themselves were developed. It was also pointed out that these follicles, which were covered with a rich net-work of fine capillary vessels, assumed the office of a respiratory apparatus, by which the gases were interchanged between the embryo and the parent fish; and, further, that this follicle also acted as an egg membrane, being actually perforated by a round opening, which the speaker termed the "follicular pore," and which was analogous to the micropyle of the ordinary fish egg. The arrangement of the follicles of the ovary within the body of the female was described at some length, and the peculiar differences between the two sexes in the arrangement of the viscera were pointed out. The fibrous bands, which act as supports, or stays, to the basal portion of the anal fin of the male, which is modified as an intromittent organ, were also described. The great difference in the sizes, of the sexes was also referred to, the female weighing over six times as much as the male. The speaker concluded by expressing his earnest desire to investigate the other known forms of viviparous fishes, such as the Embiotocoids of the West coast, the viviparous Blenny, and other bony fishes which have this habit, and which, in his opinion, would throw considerable light upon some of the peculiar physiological processes involved in the viviparous methods of develop

ment.

Mr. Romyn Hitchcock exhibited a collection of Foraminifera belonging to the genus Lagena, and made a few remarks explaining the relation between this genus and the Nodosarine group; these briefly being that Lagena may be taken as the type of the group, passing through Nodosaria and ending in Cristellaria as the most complete manifestation of its method of growth.

* 1882. RYDER, JOHN A. Structure and ovarian incubation of Gambusia patruelis, a top-minnow. <American Naturalist, Feb., 1882, pp. 109-118.

ADDRESSES AND COMMUNICATIONS.

THE PRINCIPLES OF ZOOGEOGRAPHY.*

BY THEODORE GILL.

Zoogeography, or the science of the geographical distribution of animals, may be said to have originated with the illustrious French naturalist of the last century, who inaugurated the era of philosophical zoology in about the same degree as Linnæus did that of systematic zoology, and who is also well known as the antagonist and rival of the great Swede. Many of the facts that are the bases of its propositions had indeed been known before the time of Buffon, but the relations of those facts to each other, and to the general doctrine of science, had either been entirely overlooked or were vaguely appreciated.

It is Buffon who is to be credited with having first promulgated precise generalizations respecting the geographical distribution of animals. Buffon, in this respect, not only advanced much beyond. his predecessors, but leaped at once to a position which some of the the more pretentious naturalists of our own times have failed to attain. In brief, he recognized (1) that the inhabitants of the tropical and southern portions of the old and new worlds were entirely different from each other; (2) that those of the northern portions of the two were, to a considerable extent, identical; and

*Annual presidential address delivered at the Third Anniversary Meeting of the Society, January 19, 1883, in the lecture room of the U. S. National Museum.

In the present address, previous contributions by the author to Zoogeography— the article "Zoological Geography" in Johnson's New Universal Cyclopædia, and a review of Wallace's "Geographical Distribution of Animals," published in “The Nation" for July 12 and 19, 1877, and republished in "Field and Forest,” (vol. ii, pp. 69-74, 78-80, 98-101,) have been borrowed from.