OSTODOLEPIS BREVISPINATUS, A NEW REPTILE 
FROM THE PERMIAN OF TEXAS 
S. W. WILLISTON 
University of Chicago 
In the summer of 1909 the writer found, on West Coffee Creek 
in Willsbarger County, Texas, a series of seven articulated vertebrae 
and their connected ribs, for the most part concealed in a small 
block of red sandstone. At the time of their discovery a new 
genus of reptiles was recognized in the specimen, but only recently 
has the opportunity for its further examination presented iiself. 
The removal of the concealing matrix has revealed certain unique 
characters that will justify the description of the well-preserved, 
though incomplete specimen. 
The vertebrae resemble those of Araeoscelis more closely than 
those of any other form hitherto made known from the Permocar- 
boniferous deposits of America. They also seem to resemble those 
of Tomicosaurus Case, so far as their arches are concerned—the 
centra are unknown in the latter genus—but differ in the presence 
of stout diapophyses and much greater size. The centra of 
Ostodolepis are as broad as long. The ends, as usual, are deeply 
and conically concave, with a small perforating foramen. The 
under side is gently concave longitudinally, broad from side to 
side, and gently concave in the middle transversely. Just above 
the sides of the nearly square under surface there is a shallow 
lateral fossa near the middle. The arch is low and flattened, broad 
from side to side, though not at all cotylosaurian in character, 
and has a very small, almost vestigial, tuberculiform spine. The 
zygapophyses are broad and flat, and their articular surfaces look 
almost directly upward and downward. On the lower part of 
the arch on each side, near the front end of the vertebra, there is 
a rather stout, but short, diapophysis, directed outward and a 
little downward and backward, with its free end oval in outline 
and gently cupped. Unlike any centra from Texas hitherto 
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