He also spoke of an Arceuthobium (mistletoe) from the Pacific coast, the seeds of which were forcibly expelled to some distance. Mr. Ryder described Licnophora cohnii Clap., a ciliated protozoan found on a hydroid at the mouth of Chesapeake bay. The hydroid was-parasitic on the shell of a bivalve mollusk inhabited by a hermit crab.

Oct. 25. Mr. Pike made a communication upon the celebrated insect-bearing deposits of Mazon creek, Illinois. These fossils are usually found in nodules of blue shale.

Nov. 1. Mr. Ryder stated that efforts had been made during the last two summers to delay the development of fish eggs with a view to transportation. These experiments were only partially successful. At a temperatnre of 53° development proceeded normally, but more slowly than usual, up to a certain point, when a fungus formed upon the egg membrane. Temperature slightly lower than 53° caused abnormal development, and 45° proved fatal. Professor Brooks had found in the case of oyster eggs that the phenomena of segmentation and nuclear division were rythmical, and Mr. Ryder held that there was a direct relation between these phenomena and heat as a mode of motion.

Nov. 8. Mr. Meehan said he had lately found Robinia viscosa, which he believed had never been collected by botanists since its description by Michaux, growing abundantly in gardens near the Delaware Water Gap. It was said to have been brought from the neighboring mountains. The plant produced a multitude of flowers, but very few seeds. The rose acacia of the nurseries has never been known to produce seeds.

Mr. Ryder described the development of Hippocampus. The quadrate, hyo-mandibular, and symplectic cartilages are largely developed, the intestine is provided with a curious valvular arrangement at its posterior end; and the plates, which are much fewer than in the adult, are developed as conical caps immediately under the epithelium.

Mr. Potts indicated a new species of sponge under the name of Mayenia craberiformis. Sponges occur only in flowing, drinkable water. He had found from four to six species in every stream he had examined.

Nov. 15.-The Rev. Dr. McCook spoke of the methods of escape practiced by orb-weaving spiders when thrown into the water. Some apparently formed a little raft of web for their hinder feet, and paddled ashore with their fore feet; while another further out allowed threads to float upwards from its spinnerets, and was wafted ashore by the wind. These two methods were both probably instinctive.

Nov. 22. Mr. Ryder gave the results of his studies of the division of cell nuclei. Dr. Horn described the peculiar struc

ture of the mandibles of a Balaninus which bores through hickory nuts. The mandibles are reversed, so as to move in a vertical direction.

Dec. 6.-Mr. Potts referred to three species of fresh-water sponges, the statoblasts of which are provided with long curled tendrils, homogeneous and continuous with the chitinous coat; these forms constituted the genus Carterella. Mr. Ryder stated that the silver gar and other allied fishes had eggs provided with long cylindrical filaments, which twist with those of other eggs so as to form masses of several hundreds.

Professor Rothrock stated that in Ceanothus prostratus, the chlorophyll of the leaves is confined to a layer around inwardgrowing sacs, in the interior of which are the stomata. sacs are protected by downward-growing hairs.

These

THE BIOLOGICAL SOCIETY, Washington, D. C., March 3.-The twenty-third regular meeting of the Biological Society was held at the above date in the lecture room of the National Museum, at which ninety members were present, Professor Gill in the chair. A discussion of the shape of the sea-cow's tail, continued over from the previous meeting, was carried on by Mr. H. W. Elliott, Dr. Elliott Coues, Mr. F. W. True, Dr. T. H. Bean, Mr. G. Brown Goode, and Professor Theodore Gill. The committee on lectures announced that in conjunction with a similar committee from the Anthropological Society they had arranged for a course of eight popular lectures on scientific topics. The programme is as follows: March 11, Professor Theodore Gill, "Scientific and Popular Views of Nature contrasted;" March 18, Major J. W. Powell, “Outlines of Sociology;" March 25, Professor C. V. Riley, "Little-Known Facts About Well-Known Animals;" April 1, Professor Otis T. Mason, "What is Anthropology;" April 8, Professor J. W. Chickering, Jr., "Contrasts of the Appalachian Mountains;" April 15, Dr. Robert Fletcher, Paul Broca and the French School of Anthropology;" April 22, Professor William H. Dall, "Deep-Sea Exploration; " April 29. Dr. Swan M. Burnett, "How We See." These lectures will be delivered in the lecture room of the National Museum, beginning at half-past 3 P. M.

BOSTON SOCIETY OF NATURAL HISTORY, Mar. 15.-Mr. William Trelease described the structures which favor cross-fertilization in several plants, and Mr. J. S. Kingsley remarked on the embryology of fishes.

April 5.-Professor G. F. Wright described the "Terminal moraine of the great ice period in Pennsylvania," and Mr. N. F. Merrill read a second paper on the lithological collection of the Fortieth Parallel Survey.

NEW YORK ACADEMY OF SCIENCES, Mar. 27.-Professor Thomas Egleston remarked on the proposed Government Commission for the testing of iron and steel.

April 3.-Dr. George E. Beard read a paper (with illustrations) on the psychological explanation of the Salem witchcraft excitement, and the practical lessons derived therefrom.

MIDDLESEX INSTITUTE, Feb. 28.—L. L. Dame, president, delivered an instructive lecture-the first in a series of twelve weekly botanical lectures-on the "Growth of the plant from the seed," to a class of nearly fifty members.

Mar. 7.—Mrs. A. J. Dolbear gave the second in the series, her subject being "Morphology of roots, stems and branches.”

Mar. 8.-President Dame briefly reviewed the first year's work of the Institute, and made some excellent suggestions in regard to the best manner of carrying on the work which the Institute had undertaken.

The various reports presented a most gratifying exhibit of the condition of the Institute, and its future as a permanent scientific educational force seems well assured.

Mr. Davenport announced the death of Professor Thomas P. James, an honorary member, and a committee consisting of the pres ident, W. H. Manning and Mr. Davenport was appointed to draw up suitable resolutions of respect to the memory of the deceased.

AMERICAN GEOGRAPHICAL SOCIETY, March 21.-R. E. Colston delivered an illustrated lecture on modern Egypt and its people, the army of Egypt and the military revolution in progress there the customs of marriage and divorce, and the condition of women in Mussulman countries.

:0:

SELECTED ARTICLES IN SCIENTIFIC SERIALS.

AMERICAN JOURNAL OF SCIENCE, April.-The wings of Pterodactyles, by O. C. Marsh. Sandstones having the grains in part quartz crystals, by A. A. Young. The timber line, by H. Gannett. Notice of Fisher's " Physics of the Earth's Crust," by C. E. Dutton. Great dyke of Foyaite or Elæolite-syenite in Northwestern New Jersey, by B. K. Emerson. Notice of the remarkable marine fauna occupying the outer banks off the southern coast of New England, by A. E. Verrill.

THE GEOLOGICAL MAGAZINE, March.-Supplement to a chapter in the history of meteorites, by W. Flight.

JOURNAL OF CONCHOLOGY, Oct. 1881.-Life history of Helix arbustorum, by J. W. Taylor.

THE June number of the NATURALIST will be devoted almost exclu. sively to articles on Evolution. It will contain articles by Morris, Hyatt, Cope, ▲ockington and others, with reviews of Beale, Bütschii, Loew, Pokorny, Wythe and others.

TRANSFORMATIONS OF PLANORBIS AT STEINHEIM,
WITH REMARKS ON THE EFFECTS OF
GRAVITY UPON THE FORMS OF
SHELLS AND ANIMALS.1

IN

BY ALPHEUS HYATT.

N continuation of our review in this journal for October last (p. 793) of Professor Hyatt's contribution to the evolution theory, we make the following extracts from his last condensed paper, and reproduce from the Proceedings of the American Association the plates illustrating the paper. The results of his studies on the Steinheim shells are roughly exhibited on Plate vi, and may be described briefly as follows. Figs. 1, 8, 12 and 16, are the ancestors, varieties of Planorbis levis from the older Tertiaries of another locality, identified, named, and kindly sent to me with eleven other specimens of this species by Professor G. Sandberger, who opposes the evolutionary conclusions of both Hilgendorf and myself.

From these four varieties spring four distinct lines of descent. Fig. 1 begins the series from 2-7, in which of course numbers of the connecting forms are not figured. Fig. 8 begins the series from 9-11, much shorter and containing fewer forms than in series 2-7. Fig. 12 also gives rise to a short series with only few forms. Fig. 16, however, is the starting point for a compound series, or one composed of at least three sub-series, 19-20, 21-24, and 25-28. The intermediate forms by which the gap between the four

1 From the Proceedings of the American Association for the Advancement of Science, Vol. XXIX, Boston Meeting, August, 1880.

*The author of the most complete Memoir on Tertiary shells in existence, Con. chylien d. Vorwelt.

ancestors and the four first forms of each series, viz: 2 and 9 and 17, which occur in the Steinheim basin, is very complete, but neccessarily left out in this plate.

Numbering the series from right to left we see that Series 1 has three sub-series. Two of these show a tendency to uncoil, to become distorted and smaller than the ancestor, Fig. 16, while the third decreases in size, but has a form, Fig. 20, which is turreted like Figs. 11 and 6.

Series II maintains a size about the same throughout, but becomes flatter than the originating form, Fig. 12. Series III grows sensibly larger, and 10-11 are turreted-shells with a more rigid and sub-angular form of whorl than the primal form of Fig. 8.

Series IV exhibits not only greater increase in size, but vastly greater differences in form and in other characteristics of the shell from Fig, 1, with which it started.

We can, therefore, without fear of error call series iv a highly progressive series; Series II a persistent series; sub-series 3 of Series I a partly retrogressive series; sub-series 2 of Series 1, a purely retrogressive, and sub-series 1 of Series I also partly retrogressive; since, though it decreases in size and becomes deformed and uncoiled, it also has a tendency to produce a new characteristic, the transverse ribs, and also increases in size its more closely coiled forms, as in Fig. 26.

There is also other testimony going to show that this classification is correct. Semper's researches on Lymnæus stagnalis show, that under the most favorable physical conditions, this species increases to a maximum of size and has larger whorls, while under less favorable conditions with relation to food and temperature, the size is very much decreased.

The immediate results of weakness, produced by wounds, are also important in this connection. Pl. vi, Figs. 21, 21a and 22, a diseased Pl. oxystomus, var. revertens Hilg, is a diseased specimen of the same species as Fig. 9. Pl. vi. Compare this diseased, partly uncoiled, shell with the species, Fig 23, Pl. vi, Pl. denudatus and minutus. The weakness consequent upon old age is equally significant and has a similar meaning. Pl. vii, Fig. 22, represents the effect of old age in distorting the growth of the outer whorl of Pl. oxystomus. Compare with Fig. 22, Pl. vi. These are true cases of disease of comparatively rare occurrence in Pl. oxystomus. I have in my collection many similar