282 



CAPT. D. M. S. WATSON ON SEYMOURlA, 



scapula and coracoid shows quite distinctly traces of an ossification 

 or ossifications over an area about 2 '5 cm. by 1*5 cm. This bone 

 is of very open texture'and has no definite surface, it was exposed 

 so irregularly in development and its matrix is so extremely hard 

 that no account of its shape can be given. It is certain that it 

 does not represent a series of abdominal ribs or other dermal 

 ossifications. It does not show any tendency to form long 

 columns such as sternal ribs would be, and must apparently re- 

 present a sternum, the first evidence of an ossification in this 

 element in a Lower Permian reptile. 



Text-figure 11. 



* 



Seymouria bayloriensis Broili. — Right side of the pelvis, X §. 

 From my skeleton. 



Pelvis. — The perfect pelvis of my skeleton agrees very well 

 with Prof. Williston's figures and description, but the very 

 well exposed ilia show certain significant differences from the 

 young bone figured by Williston ('American Permian Vertebrates,' 

 pi. xxix. fig. 7). In them that part of the bone which lies 

 behind the acetabulum and articulates with the ischium is quite 

 large, and a more interesting difference is that the upper margin 

 of the bone has a distinct projection towards its anterior end. 

 This feature is shown by both right and left ilia. 



Femur. — The two well-preserved femora of my skeleton agree 

 generally with Williston's figures, but appear to be considerably 

 less massive. The lower end is very markedly divided into 

 condyles. 



Tarsus. — Both hind limbs are in position with the femur 

 directed forward with its head in the acetabulum. The knees 

 are very strongly flexed. The right foot lies naturally articu- 

 lated, but has been slightly laterally compressed, so as to slide 

 the head of the third over that of the fourth metatarsal. Only 

 four tarsals are preserved, and it appears extremel}' unlikely that 

 any more were ossified at the death of the individual. The 

 tarsus and foot are exposed from the plantar surface. 



There are three proximal tarsals all closely , articulated with 

 one another and with the tibia, but separated by an interval 

 of about 8 mm. from the fibula. 



