prevented the formation of a jet. Instead of this, several square inches of the cloth were covered with a bright glow, somewhat resembling that on the positive ball, but, unlike that, seemingly made up of innumerable minute points or patches of light, having a peculiar swarming motion, like that described by Neef in his researches upon the negative discharge as seen under the microscope. When the paper grating was placed between the poles, the image on the positive was not readily obtained with distinctness, but was generally much smaller than when the negative pole was not thus covered.

A similar effect, but much more brilliant, was produced when, the poles being separated nine or ten inches, the hand was placed upon the negative, and the arm was approached to the positive pole. The woolen sleeve exhibited a bright glow covering a large area, and appearing like a strongly phosphorescent powder sifted profusely upon it. When this was approached so near that the interval was only an inch and one half or an inch, the positive glow became much more intense, and took a delicate purplish tinge, and the whole space between the two was filled with a very faint auroral light, which appeared, unlike other forms of the discharge, to be perfectly continuous and steady. The dark discharge under these circumstances was evidently so much intensified as to become luminous and visible.

Williamstown, Mass., April 22, 1871.

ART. LXV.-Brief Contributions to Zoology from the Museum of Yale College. No. XIV.-Descriptions of new and imperfectly known Ascidians from New England; by A. E. VERRILL.

[Continued from page 294.]

Family, DIDEMNIDE.

In this family we include, together with the typical genera, Leptoclinum and its allies, which have been separated as a distinct family (Leptoclinida) by Prof. Gill.* There appears to be no definite ground for such a distinction. The genera Didemnum and Leptoclinum are very closely allied, and scarcely distinguishable so far as the structure of the individual zoöids is concerned, the difference being chiefly in the mode of aggregation. Such differences are generally of too little importance among compound animals to form the basis of family distinctions, unless accompanied by important differences in the individuals themselves.

* Arrangement of the Families of Mollusks, p. 23, 1871.

Lissoclinum, gen. nov.

Allied to Leptoclinum. The colonies form more or less broad, thin, encrusting masses or sheets, soft and somewhat gelatinous in texture, without calcareous corpuscles. The zoöids are arranged in more or less irregular, scattered systems, consisting of many individuals placed along cloacal ducts, which are connected with common external orifices. Branchial region, or "thorax," equal to or larger than the abdominal. Branchial orifice with six papillæ. Anal orifice lateral or subterminal, prominent. Abdomen separated from thorax by a short peduncle. Stomach with longitudinal glandular ridges. Ovary sublateral, when filled with eggs projecting backward beyond the abdominal viscera. Eggs large.

This genus differs from Didemum* and Eucalium in having common cloacal ducts and orifices, as well as in the form and position of the abdomen and ovary. From Leptoclinum it differs in the soft gelatinous texture and in the form and structure of the zoöids.

Besides the two following species, this genus appears to include L. gelatinosum and L. Listerianum, both of which were referred to Leptoclinum by Milne Edwards.

Lissoclinum aureum, sp. nov. Figure 26.

26

b

C

Colonies encrusting, forming nearly flat masses, about 15 to 20 of an inch thick, and up to an inch or more in diameter. Texture soft and gelatinous, semi-transparent. Systems irregular, consisting of many individuals arranged along the elongated, common cloacal ducts. Branchial orifice with six rather elongated and slender papillæ. Branchial sac broad and laterally extended, with the transverse ves- d sels quite distinct, and the longitudinal ones less so. The oesophagus is short; stomach more or less oval and elongated, with well-marked longitudinal ridges or glands; intestine large, prolonged toward the anal orifice. The anal tube is nearly terminal, conical, and more or less prominent. Ovary lateral, when full of eggs projecting backward beyond the end of the abdomen. Color of the common mass light yellow; zooids bright orange.

0

Figure 26, Lissoclinum aureum V.-One of the zoöids, enlarged 10 diameters; a, anal orifice; b, branchial orifice; c, branchial sac; d, oesophagus; e, stomach; g, end of intestine; o, ovary distended with eggs of various sizes; r, "marginal tube" or pedicle of a bud; s, spermatic duct. (From a camera-lucida drawing by the author).

*The genus, Didemum, as established by Savigny and adopted by Milne Edwards, includes two distinct groups: the first having calcareous corpuscles in its integument; the second soft and gelatinous throughout. The latter may be called Lioclinum. It includes L. viscosum (Sav.) and L. gelatinosum (Edw.).

The zooids, as preserved in glycerine, are 10 to 13 of an inch long; breadth, across branchial sac, 05 to 07; across abdomen, 05 to 06; length of thorax 04 to 07; of peduncle 005 to 010; of abdomen 045 to 055.

Eastport Harbor, 12 to 20 fathoins,-Expedition of 1870.

The cloacal ducts of a specimen taken in August, were found to be filled with chains of eggs containing the tadpole-shaped embryos in an advanced stage of development. No eggs or embryos were observed in the atrium of the numerous zooids examined.

Lissoclinum tenerum, sp. nov.

Colonies encrusting shells, ascidians, etc., forming thin, soft, gelatinous crusts, which are translucent, and filled with numerous, very small zoöids, which are nearly uniformly distributed. Cloacal openings small, round, numerously scattered over the surface. Zooids have the branchial region more elongated and narrower than in the preceding species, with a somewhat larger peduncle between it and the abdomen, and with the latter, exclusive of the distended ovaries, smaller than the branchial region. Stomach elongated, longitudinally ribbed. Branchial tube elongated, with six short papillæ; anal short, broad, lateral, below the middle of the branchial sac, slightly six-lobed. Color not observed in life; in alcohol transparent whitish, with yellowish white zoöids.

The colonies are up to two inches in diameter and 10 to 12 thick; zooids about 07 long; the thorax 032, by 02 wide; the abdomen 025 long, by 015 in diameter, exclusive of the distended ovaries, which in some cases are as large as the entire body.

Eastport, Me., 10 to 40 fathoms, shelly bottom,-Exp. 1870; Banks of Newfoundland,-T. M. Coffin.

This species may be easily distinguished from the preceding by the very small zoöids and paler color. The zoöids are very different in form, owing to the lateral position of the anal orifice. The stomach is remarkably elongated and slender in young individuals, projecting into a posterior prolongation of the abdomen. The eggs are few and relatively very large. Many of them appear to become detached by rupturing the membranes of the ovary, and escaping into the gelatinous common tissue, develop there.

The development of such eggs* is direct, without passing through a tadpole-shaped larval state. Scattered through the common gelatinous mass, young ones may be found in all

*With the alcoholic specimens it is not possible to trace completely the early stages of this development, or to be perfectly certain that these egg-like bodies are genuine eggs, although some of them appear to contain, at first, a germinal vesicle.

stages of development.

The branchial and anal tubes are widely separated in the young, and the stomach projects backward beyond the body.

Leptoclinum albidum, sp. nov.

Colonies encrusting stones, dead shells, ascidians, etc., forming broad, thin, irregular, coriaceous crusts, with an uneven surface, filled with minute, white, spherical, calcareous grains or corpuscles, which, under the microscope, have the surface covered with projecting points. Surface of the crusts covered with small, irregular, scattered prominences, in which the branchial orifices are situated. Cloacal orifices few and distantly scattered. Systems irregular, the zooids scattered, but often arranged in rather indistinct concentric circles around the cloacal openings. Color white, the zoöids light yellowish.

The colonies often become 1 to 2 inches across, sometimes 2 inches or more long, and only 25 or less wide; thickness seldom more than 10, commonly about 05; zoöids 02 to 03 long; diameter 01 to 012 of an inch.

Eastport, Me., low water on under side of rocks, to 100 fathoms on stony and shelly bottoms, common.-Expeditions of 1863, 64, 68, 70; Grand Menan, 10 to 15 fathoms,-Exp. 1870; Labrador,-A. S. Packard; Mingan Islands, Lab.-A. Ê. Verrill; Banks of Newfoundland, T. M. Coffin; Thimble Islands (near New Haven), Conn., 6 fathoms, on rocky bottom,A. E. Verrill.

Leptoclinum luteolum, sp. nov.

This species forms thin, coriaceous crusts, like the preceding, and filled in the same way with similar spherical corpuscles. The branchial orifices open at the summits of low verruca. The cloacal orifices are small, with four to six lobes, and distantly scattered. Color deep salmon, or somewhat rosy.

The crusts are of all sizes up to 2 inches or more in diameter, and are usually somewhat thicker than in the preceding species, with larger and darker colored zoöids.

Eastport, Me., and Grand Menan, with the preceding species,-Expeditions of 1861, '63, '64, '68, '70,

Under the name of "Didemnium roseum Sars" Dr. Packard* probably included both this and the preceding species. Mr. Binney, in the second edition of Gould's Invert. of Mass., has merely copied from Dr. Packard's work.

* Memoirs of the Boston Society of Natural History, vol. i, p. 276, 1867.

ART. LXVI.-Notice of some new Fossil Reptiles from the Cretaceous and Tertiary Formations; by O. C. MARSH, Professor of Paleontology in Yale College.

THE remains briefly described in the present preliminary notice were collected by the Yale College party during their explorations last summer in the Rocky Mountain region. The specimens from the Cretaceous formation are of great interest, as they further illustrate the remarkable development in this country, both in numbers and distinct forms, of the Mosasauroid Reptiles, which appear to have been comparatively rare in other parts of the world. Fortunately, moreover, some of these remains serve to clear up several obscure points in the structure of these reptiles, and prove conclusively that they had a well developed pelvic arch and posterior limbs; although up to the present time no satisfactory indication of this had been discovered, and the eminent paleontologists who have recently made these animals an especial study consider them probably destitute of these extremities. The remains found in the Tertiary deposits are also of importance, since they show that types of reptilian life, almost unknown hitherto from that formation in the West, were, in one of the ancient lake-basins at least, abundantly represented there during that period.

CRETACEOUS REPTILES.

Edestosaurus dispar, gen. et sp. nov.

This genus, which so far as now known includes but two species of small Mosasauroids, is especially distinguished from Clidastes, its nearest ally, by the insertion of the pterygoid teeth, which are pleurodont in the anterior half of the series, and in the posterior portion have the outer dental margin protected by a low parapet of bone. From Platecarpus, the genus is widely separated by the zygosphene articulation of the vertebræ. The pelvic arch and posterior limbs were well developed, but there was apparently no sacrum.

The present species is mainly established on the more impor tant parts of a skeleton, including the greater portion of the skull, both quadrates, about seventy vertebræ, parts of the scapular and pelvic arches, and fragments of the limbs. The remains are in an excellent state of preservation; and indicate a Mosasauroid reptile, apparently about thirty feet in length, or near the size of Clidastes iguanavus Cope.

The vertebræ possess the complete zygosphene articulation. In the cervicals and anterior dorsals, the cup and ball are somewhat inclined; in the posterior dorsals and lumbars, less so;

* Edɛoris, devourer, and Zaupos, lizard.