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5. W. WILLISTON 



coracoid surface. The proximal end of the right humerus lies per- 

 fectly in position in the glenoid fossa. The distal extremity of the 

 bone, twisted in a plane nearly at right angles with that of the proxi- 

 mal, presents not the slightest indication of an entepicondylar foramen, 

 and the bone is not at all mutilated. The absence of this foramen is, 

 however, extraordinary, since very nearly all the known reptilian 

 vertebrates of the Permian have it, though not all, according to Cope. 

 The thinned margin of the proximal expansion has been lost in the 

 specimen. There is the possibility, a remote one I believe in view 



of the fact that the relations of 

 the various bones of the skeleton 

 had suffered little disturbance, 

 that the humerus had been com- 

 pletely and perfectly reversed in 

 the glenoid socket, and some in- 

 dication of this reversion is fur- 

 nished in that the so-called distal 

 end agrees fairly well with the 

 proximal end of some forms. 



In the structure of the feet I 

 have no emendations to make of 

 Professor Case's interpretations, 

 save of the centrale of the pes. 

 This bone I find, on removal of 

 the bone lying over it, to be pretty 

 well fused with the tibiale, the 

 union shown, however, clearly in a 

 suturalline. Broom has expressed 

 a doubt of the structure of the 

 feet in this specimen. There can be none. The number and 

 arrangement of the bones of the carpus are assuredly as Case has 

 figured them. As to the number of the phalanges in the digits I 

 believe that they will be found to be as in Procolophon and Telerpeton, 

 2, 3, 4, 5, 3, or 4. The pelvic girdle in this specimen is typically 

 that of the old reptiles, elongated, fiat, plate-like pubes and ischia, 

 closely united by suture and wholly without a thyroid foramen. It 

 is the pelvis of Procolophon, Telerpeton, Paleohatteria, etc. 



Fig. 5. — Hind foot of Lahidosaurus 

 incisivus; natural size. T, tibia; F, fibula; 

 Tb, tibiale; Fb, fibulare; C, centrale; 1-5, 

 distal tarsals; I-V, metatarsals. 



