316 



SAMUEL W. WILLISTON 



tion in the temnospondylous amphibians and in Diplocaulus. 

 There was literally no neck in the cotylosaurs. In three of these 

 specimens the shaft of the clavicles is turned dorsad at a right 

 angle to the lower, horizontal, and expanded part; in two or three 

 others the angle is slightly greater. In one specimen, that shown 

 in Fig. i, lying in immediate connection with the upper end of the 



Fig. 5. — Labidosanrus. A, front leg; B, hind leg; C, clavicular girdle clavicles 

 from below, interclavicle from below, clavicles from in front; D, humerus ventral 

 face; E, scapula, outer face (No. 634). All figures about one-half natural size. 



clavicle, there is a very slender bone about 20 mm. in length; a 

 similar bone is also found in specimen No. 178 with quite the same 

 relations. There would seem to be little doubt that it is a vestigial 

 cleithrum. In Limnoscelis the cleithrum is very small, though 

 much larger in Diadectes. None has been observed in Seymonria, 

 but I am inclined to believe that all the American cotylosaurs 

 possessed the element, though in some cases it was vestigial. The 

 scapula figured (Fig. 5, E), is quite complete, but is lying on its 



