154 E. C. CASE 



total length of the bone is o.i57 m . The width of the lower end is 



O.I02 m . 



The femur. — The femur is of a very simple type. There is no 

 distinct head, and there is the usual concavity on the anterior face 

 near the proximal end. There is a low but distinct ridge connecting 

 the upper and lower ends on the anterior (inferior) face which crosses 

 the bone somewhat obliquely. The distal condyles are almost entirely 

 on the anterior face. The length of the bone is 0.150 111 . 



Only the proximal ends of the bones of the forelegs remain, but 

 these, with the described bones of specimen No. 62, show that they 

 were proportionately short and stout. In the description of speci- 

 men No. 62 figures were given showing that the phalanges were 

 short, and that the foot must have been short and strong, with stout 

 nails or claws, perhaps fitted for digging. Unfortunately, no attempt 

 can be made to give the phalangeal formula. 



Form and habits. — Cope makes the following suggestions regarding 

 the Diadectidae: 



There is some reason to believe that the Diadectes relied exclusively upon 

 the pineal eye for the sense of sight. The species of the family were subterranean 

 in their habits, since their humeri indicate great fossorial powers, resembling 

 those of the existing monotremes and even the moles. The vertebrae are locked 

 together with hyposphen beside the usual articulations, and the arches of the 

 neural canal form an uninterrupted roof from the skull to the tail, of extraordinary 

 thickness and strength. That the species are not aquatic is rendered probable 

 by the fact that the orbits do not look upward. Their superior borders are, on 

 the contrary, prominent and straight. Add to this fact the apparent absence of 

 optic foramina, and the probability that the Diadectidae were blind and subterra- 

 nean in their habits becomes still stronger. 



There seems little doubt that the points made by Cope are in the 

 main correct. The animals were undoubtedly flat of body and 

 strong of limb in regard to their digging powers. It may be doubted, 

 however, if there is sufficient evidence to warrant the suggestion that 

 they were blind. If they resembled the turtles as much as seems 

 probable, it is very possible that the optic nerves escaped from the 

 brain case in the same way without any special foramen. 



It will be seen from the above description that the family Dia- 

 dectidae must be removed from the Cotylosauria and placed in the 

 order Chelydosauria. It also supports in a most striking manner the 



