278 THE BATH OOLITE PERIOD. CHAP. 



The pubis (i) and ischium (2) are represented on one plane, to shew the true figure 

 of each. The ilium is marked by words only, to shew its position in a general manner. 

 The ischial bone is incomplete at the medial symphysis s' s'. "The pubis is only 

 incomplete along the anterior edge ; it was complete while in the ground. /. The 

 foramen. ss. The symphysis. a. The junction of pubis and ischium, to form 

 the inner and lower border of the acetabulum. 3. Pelvic girdle of Begenia ocellata. 



The comparison thus made is supported by the other element of 

 the pelvic girdle represented in the same Diagram by fig. 2 the 

 ischium. This bone is complete except in the part near the medial 

 symphysis, which is sketched at / s from general analogies. Its 

 anterior edge is a deeply concave curve opposed to that of the 

 pubis, with which it makes contact in a line directed to the 

 middle of the acetabulum. From this line the acetabular curve, 

 matching that of the pubis, curves outward to the rough surface 

 which formed the attachment to the ilium. In all this the bone 

 is like the ischium of the monitors ; and probably both it and the 

 pubis were attached to the ilium, much as they are in the well- 

 known lizard, Varanus niloticus. The small accessory pieces of 

 a lozenge figure which are seen in Regenia to extend the symphysis, 

 have not been observed in the fossil. 



Diagram (77. Ilium of Ceteosaurus, seen on the external face. Scale, one- 

 tenth of nature. a b. The acetabulum. 



With great difficulty the separated parts of one ilium were first 

 refitted, with the exception of the upper and middle portion of the bone. 

 Then a second specimen, of the opposite side, was adjusted, both 

 awkwardly crushed. The extreme length of one is 42, of the other 45 

 inches, probably equal to six vertebrae ; the chord of the acetabular 

 socket is 1 8 ; from the angular boundary of this socket, across the 



