5 
lateral ridges of J. triangulata are situated low down on the centra. The 
diapophyses supporting the tubercular articulation are frequently elongate. 
The scapular and pelvic bones are of the usual type. The humeri be- 
long to form second of my Pal. Bull. No. 29. They have rather slender 
shafts, and much expanded extremities. The proximal articular surface is 
well defined. The supracondylar foramen and other points are as in the 
Pelycosauria generally. There were probably distal condyles, but this is 
not absolutely certain. 
Measurements. M... 
Length of mandibular series of teeth (nearly complete), 
OD, DOCK is as es neidiens saa ea endteeee dee watermncen -110 
Length of crown of mandibular tooth......... eaaviveiainibis 008 
Anteroposterior diameter of mandibular tooth......... 004 
Diameters of articular extremities of a ver- (vertical... .021 
tebra on the same block...........-6 Linmnererse. 020 
Length of another centrum on same block............. 020 
larger... .065 
ab Dead { smaller. .015 
Of shafthe cc icwe secs O17 
The above description represents the parts which belong either certainly 
or very probably to one individual. Bones of asecond and larger animal are 
mingled with these. The species to which they belong is uncertain, but 
they resemble very much those of the Theropleura obtusidens, and may be- 
long to a larger individual of that species. A femur has the form already 
described under the head of Clepsydrops natalis. (Paleontological Bulletin, 
No. 29, p. 510.) Some phalanges belonging no doubt to one or the other of 
the two animals, are like those I have already ascribed to Clepsydrops. 
They are depressed, and are expanded at the articular extremities. The 
distal extremities expand the most abruptly. and their convex trochlear face 
is without groove or keel, and is more extended on the inferior than the 
superior surface. 
Diameters of humerus (separate) | 
DIMETRODON Cope. 
Proceedings American Philosophical Society, 1878, p. 512. 
The accession of a considerable amount of material representing this 
genus enables me to add importaut points to our knowledge of its osteology. 
The most noteworthy additions include the greater part of the skeletons 
of two individuals of D. incisivus ; and vertebrae attached to the pelvis 
and femora of D. gigas. There are also vertebra of several individuals of 
D. cruciger, and various parts of the skull of a species distinct from the D. 
incisivus. : 
In both specimens of D. incisivus, portions of the palatopterygoid arch 
are attached to the maxillary bone. One of these elements is an oval plate 
with a thickening of its inferior side, so as to bevel the long border farthest 
fron the maxillary bone. The surface thus produced is thickly studded 
with small conical teeth irregularly disposed. 
A second tovth-bearing element of the palate is adjacent to the last. It 
