shaped plates, bending much down towards the orbits, and terminating in an obtuse angle, they form together a zigzag line, in which are placed three large plates; the middle one being a hexagon, broad below and narrow above: the two side ones form the upper edge of the orbits, and resemble somewhat the middle one in an inverted position; and one of the angles, where it forms part of the orbit, is truncated. The two following plates, which terminate the number, fit in a less regular zigzag line, formed by the three hexagons, and, both combined, form a half circle, reaching to about the occiput of of an inch behind the eyes. The eyes, besides the plate which forms the upper edge, are surrounded by ten trapezoidal, or rather cuneiform plates. The lips are covered with twice eight plates, which increase in size towards the back part of the mouth: the lower lip is covered with twice ten plates, increasing in size in a contrary direction.

The whole snake is rather thick; the circumference of the one of which the dimensions are given being rather more than four inches.

The dorsal scales are very long, oval, and slightly carinated. The colour above is uniformly black; below the head it is yellowish white; the abdomen gray, or bluish white.

It is generally known under the name of Spreading Adder, and is much dreaded. Though quite harmless, the Heterodon is a vicious snake: and when it perceives that it cannot escape its antagonist by running, it then prepares for battle, makes a very hissing noise, and flattens its head more than any other snake, then darts at any thing presented to it. But when a little roughly handled, even without hurting it, as pushing it with a stick a few times from one place to another, it will feign to be dead. In such state I carried for some time the first that I met with, imagining that it was really dead; but when I arrived at my lodging I laid my snake down, to prepare a bottle to put it in; when, lo! after a few minutes, it made its escape, and I had difficulty to find it.

One of those that I dissected was a female: she had 140 abdominal plates; and I found in her 25 eggs, of an oval shape, three quarters of an inch long, without calcareous cover.

Sp. II. HETERODON ANNULATUS.

Heterodon annulatus; annulis latis et alternatim nigris et aurantiis dispositis.

Head 1 in. of which the large plates occupy

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The form of the dorsal scales is similar to those of the H. niger.

The general form of the H. annulatus coincides pretty much with that of the H. niger, but is rather more slender. The disposition of the plates on the head, and the form of the scales covering the back part of the head, are also similar to those of the preceding.

The body is regularly surrounded with black and orange rings. The head is perfectly black; and immediately behind it is the first orange ring, which continues alternating with black rings, till the very extremity of the tail, forming 31 orange and 30 black rings; which nevertheless do not surround the whole body, but run only from one side of the abdominal plates towards the other. Below it is yellowish white.

I found this reptile in Perry county, in the western district, Tenn. I am not acquainted with its habits, but I suppose it frequents, in preference, swampy places; such was the place where I found it. The inhabitants told me that it was not uncommon, they also called it Moccason.

Heterodon tigrinus. Colore cinereo cum maculis ovatis nigris dorsalibus, aliisque maculis rotundis et nigris in utroque

Head 1 inch, of which the large plates cover

The form of the dorsal scales, and the plates on the head, is similar to that of the two preceding species; also the general appearance is pretty much like the H. niger and H. annulatus, but it differs much in size. I never saw any specimen longer than 16 inches; all that I have seen were shorter.

This species is very beautifully variegated: the generality of the colours is black and ash gray: which is, in the young ones, light, and in the old ones dark, approaching to brown. A black stripe, commencing at the corner of the mouth, runs in an oblique direction over the eye to above the little oval plate; where, crossing the head, it runs over the other eye to the other corner of the mouth, forming a figure approaching to that of the horse-shoe. Two black spots run from the two, terminating large plates, diverging at first, but afterwards they approach one another again. At the point where they are the farthest apart is an elongated oval spot. These spots are repeated over the whole body; they are about of an inch long, and are of an inch apart. On each side is a row of smaller circular black spots, placed below the intervals between the oval ones: this arrangement continues on to the tail, on which the same colours are arranged in regular bands.

The lower part is yellowish white under the head, gray under the body, and white under the tail.

I found one near my dwelling, near the University of Nashville; and I received another from Mr. Skipwith, Maury co. Tenn. it was considered by him as a Highland Moccason.

The H. tigrinus and annulatus are both of rare occurrence.

I have amongst my reptiles, collected in Tennessee, several Colubers, which are not mentioned by those whose writings on these animals have come under my perusal; these I intend to describe in a continuation of this memoir.

Note by the Author.-Having inadvertently employed the name Acontias, which is preoccupied, I request the reader to substitute Toxicophis in place of it.

A MONOGRAPH of the North American species of RHYNCHOSPORA. By ASA GRAY, M. D.

Read December, 1834.

The natural order CYPERACEA has, in proportion to the number of species it comprises, been less carefully studied than any other family of phenogamous plants. Notwithstanding the researches of R. Brown, Kunth, Nees von Esenbeck, &c. who have illustrated particular portions of this family, the distinctive characters of the genera are, in many cases, highly unsatisfactory, and the determination of species is frequently difficult. The whole order requires an elaborate revision by some competent person, who can consult the principal herbaria of preceding botanists, as well as many important works, which, from their great cost or extreme scarcity, are inaccessible to us.But the plants of any single country may be most advantageously studied by a botanist who is familiar with them in their native situations, and who has opportunities of examining and comparing with each other numerous specimens from various localities.

A person who in this way confines his attention, for a time at least, to the critical examination of a single genus or family of plants, and who carefully records the facts which he observes, may furnish important materials to those who, with more ample means, are to succeed him in the same field; and thus contribute, in some degree, to the advancement of the cause of science.

The following account of the North American species of Rhynchospora has been prepared under circumstances highly favourable for arriving at correct results. With a liberality which does honour to the cause in which they are engaged, my botanical friends have placed their collections at my disposal VOL. III

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