1895.]

[Cope.

The parasphenoid bone widens anteriorly so that the pterygoid foramina are triangular with the base posterior and the apex anterior. At the extremities of the transverse processes of the parasphenoid the pterygoids send a prominent border downwards; they then curve rather abruptly outwards to the quadrates. The teeth have not been fully exposed, but on the middle of the length of the maxillary bones they are small and widely spaced.

It is uncertain whether there is a process at the inner side of the tabulare as in Z. serratus. The region of the occipital condyle is without projection and is like that of other species of the genus.

ZATRACHYS CONCHIGERUS, sp. nov.

This ganocephalous batrachian is known to me from the posterior part of the cranium of an individual of about the size of the smaller specimen of the species just described. It differs from this and from the Z. serratus in two conspicuous characters. First, the tabular processes are smaller and more widely separated from each other; second, the border of the quadratojugal element projects freely from the distal part of the quadrate, and is separated from it by an open emargination. The orbits are not so small as in Z. microphthalmus, have a raised border, and are posteriorly placed. Their diameter is about equal to the space between their posterior border and the tabuloquadrate notch, and is about half the interorbital width. The tabular processes are quite small, and the border connecting them is depressed in the center. The surface is strongly rugose.

The occipital condyles are represented by two shallow cotyli, which are confluent on the middle line. The posterior part of the pterygoid forms a sharp curve inwards before reaching the quadrate, and presents a thin edge inferiorly. The free edge of the quadratojugal is serrate. The muz zle of this specimen is broken off a short distance anterior to the orbits. Dimensions.

MM.

56

74

20

25

10

Cope.]

[Nov. 15,

TRIMERORHACHIS MESOPS, sp. nov.

The greater part of the skull and vertebral column with ribs and thoracic plates represent this species. The vertebral column and ribs rest in a sheet of matrix whose upturned edges suggest that it contains as a support a ventral armature. It also looks like a cast of a cavity left in the matrix by the dissolution of the inferior body wall. The only part of the vertebræ discernible without further cleaning are the neural arches. Limbs not detected. The posterior border of the skull is damaged, but one angle is preserved, and all of the other but the apex. The remainder is in good preservation on one side or the other, and the surface has been cleaned by weathering. The lower jaw is tightly closed on the upper.

The skull does not expand posteriorly as in the T. insignis. The posterior border of the orbit is 4.5 times the diameter of the latter in front of the angle of the mandible, and four times posterior to the line of the end of the muzzle. It is thus nearly in the middle of the length of the skull, and posterior to the position it holds in the T. insignis. The interorbital space is nearly twice as wide as the diameter of the orbit, while in T. insignis it equals that diameter. The muzzle is therefore relatively elongate, and it projects an eye diameter beyond the line connecting the anterior borders of the nostrils. The latter are large and look upwards; and the long or anteroposterior diameter equals the transverse diameter of the orbit. There are no preorbital or interorbital depressions. The sculp ture is strongly marked. On the jaws it is generally longitudinal; on the supratemporal, radiating; on the top of the front and muzzle, reticulate with some predominance of the longitudinal ridges. The sensory grooves are very obscure, but are traceable on the internal border of the nostrils, but scarcely posterior to them. The groove on the internal side of the inferior border of the mandibular ramus is distinct. The rami are more transversely expanded than in the specimens of T. insignis, but some of this may be distortion due to pressure. The parasphenoid is narrow for the greater part of the length.

The T. bilobatus is known from the angles of mandibles of two individuals, and probably by associated remains. The corresponding parts of the T. mesops are much more expanded transversely inwards, are horizontal in fact, where the inner wall is in the T. bilobatus, vertical. The strong internal keel of the latter, if represented at all in the T. mesops, has an external position.

The neurapophyses of the vertebræ are more elevated and more delicate than in the T. insignis, and have the usual median longitudinal groove between them on the middle line above.

The thoracic shield is represented by a coarsely sculptured plate which is but partially exposed, so that its form is as yet uncertain. The species is smaller than the T. insignis.

DIPLOCAULUS MAGNICORNIS Cope, Proceeds. Amer. Philos. Soc., 1882, p.453. This is an abundant species in the Permian beds in Texas. I take advantage of a specimen in which the skull is better preserved than in the type, to describe its segmentation, and also the disposition of the teeth.

In the typical specimen the posterior border of the skull was not preserved. The present specimen shows that it is continuous from the extremity of one horn to that of the other, and regularly concave without angles, and that it overhangs the occipital condyles a little. The posterior parts of the horns consist of the tabular bones, and the anterior portion consists of the supratemporals. The inferior part of the base of the horn externally consists of the element which articulates with the quadrate, or quadratojugal. It is distinguished from the supratemporal by a horizontal suture. A considerable part of its surface presents inferiorly. The supramastoid lies between the supratemporal and the post frontoörbital.

The supraoccipitals extend well forwards on the superior face of the cranium, the median suture equaling the length of the parietal bone. They have an extraordinary transverse extent. The median suture of the parietals is rather longer, and it is separated by the small parietal foramen at a point one-third its length from the frontal suture. The posterior width of the frontal is equal to three-fifths its length, and is a little greater than the interorbital width. It extends as far anterior as posterior to the orbits. The posterior suture is trilobate. The post frontals are suboval with the long diameter at 450 to the median line, and the anterointernal border excavated by the orbit. They do not advance on the internal border of the latter, resembling the prefrontals in this respect. The supramastoids are necessarily well produced forwards to meet the short post frontals, advancing far anterior to the posterior border of the jugals.

The premaxillaries are short and wide, and are widely truncate by the frontal posteriorly. The prefrontals do not extend posteriorly to the inner border of the orbit, but they join the jugal by a considerable suture. The nasals occupy their usual position, and are rather small; one of them is fused with the premaxillary in the specimen. The maxillaries are small, especially the facial part, which does not reach the orbit. The jugal is a relatively large bone, and has an irregular posterior outline, where it joins the quadratojugal and the supratemporal. The great expansion of the roof-bones posterior to the quadrates, is associated with a considerable expansion of the pterygoids in the same PROC. AMER. PHILOS. SOC. XXXIV. 149. 3 F. PRINTED FEB. 18, 1896.

region. The palatopterygoid arch has the relations prevalent in the Stegocephalia, but what is novel so far, its anterior and chiefly palatine portion carries a single series of teeth on the external and anterior border, which is concentric with the premaxillo-maxillary series, as in Cryptobranchus. Posterior to this is a pair of straight series of teeth, probably on the vomers, which form an anteriorly directed right-angle at the middle line. They do not extend so far posteriorly as do the maxillary teeth, and the latter do not extend so far posteriorly as the pterygopalatines, which terminate at a straight line drawn through the posterior borders of the orbits. The posterior nostrils are situated between the two series of palatal teeth. The external nostrils open forwards and outwards. Maxillary and premaxillary teeth twenty-three on each side. Palatines, twenty-four; vomerines, ten.

The composition of the huge horns is thus the result of the fusion of the three posterolateral roof-elements into one, thus obliterating the notch which separates the tabular from the quadratojugal bones in most other Stegocephalia.

DIPLOCAULUS LIMBATUS, sp. nov.

This species is represented by a number of fragmentary skeletons and skulls. One of these I describe as the type since it displays more of the characters than any other, but it is nevertheless damaged anterior to the orbits, so that the form of the muzzle is not accurately determinable.

The character of the species is seen in the horns. These are much less produced relatively to other regions than in the D. magnicornis, and the postquadrate (quadratojugal) element is more distinct, and terminates in a separate apex below the principal horn. This tract, which is fused with the principal bone in the D. magnicornis, is separated from it by a groove in the D limbatus, and the large fossa which it encloses with the inferior side of the principal horn looks inwards at an angle of 450, while it looks downwards in the D. magnicornis. The terminal angle of the quadratojugal (postquadrate) body forms a prominent compressed offset, rather than a free apex. In one specimen of large size it is infero-lateral; in the type, entirely inferior. The principal horn is shorter and narrower than in the D. magnicornis, and less divaricate.

As the mandibular rami are in place and their extremities are entire, the length of the muzzle can be inferred. It is relatively longer and less broadly rounded than in the D. magnicornis. The surfaces of the skull are sculptured in honeycomb pattern, as in the type species.