32 Batrachia of the Permian Period of North America. [Januaty, 
embryology, but whether true in any instance in paleontological | 
history yet remains to be ascertained. 
TRIMERORHACHIS Cope. 
This genus presents the most imperfect vertebrae known in the ~ 
order. It differs from all others, including Archegosaurus, in the 
lack of a distinct neural spine. Its humeri do not display condyles, — 
but had cartilaginous articular surfaces. The teeth are rather small 
Fig. ga evorhachis insignis, skull ae above ; one-half natural size. Smal 
figure; sti ly prea sculpture and nare 
and of equal size, except a large one or two inside the external 
series near the anterior part of the mouth. 
Two species are known, the 7: insignis Cope, and T. bilobatus 
Cope, both from the Permian beds of Texas. Both were pro 
bly of slender proportions, and had short weak limbs. The 
head of the T. insignis is wide, flat and rounded, and its superior 
surface is strongly wrinkled. The iyriform mucous groove 
1 This proportion is not certainly known. - 
