406 ALICE JOHNSON. 



Lizards with that of Chelonia. In both Lizards and Chelouia 

 the pubes are directed forwards from the acetabulum, and form 

 a symphysis. The angle at the symphysis is generally much 

 greater than that in Mammals. Li some Chelonia it is even 

 greater than 180°. Li both Lizards and Chelonia a process is 

 given oif from the outer side of the pubis. In the latter group 

 it is often very large (see fig. 13), and is directed forwards, out- 

 wards, and somewhat downwards. In Lizards it is not so large, 

 but still considerable, or it rnay be absent. It is generally 

 directed outwards and downwards ; but in some forms, such as 

 Cyclodus (see fig. 14), it curves backwards and slightly inwards. 

 In this case we could hardly compare it with the process found 

 in Chelonia were it not for the many intermediate forms exist- 

 ing between these two extreme types. The process in question 

 is the processus lateralis pubis. In Crocodiles it is 

 absent. 



In the Urodela the pubes are generally represented by an 

 unpaired cartilaginous plate, not clearly marked off from the 

 ischium, which is often ossified. Rarely the pubis itself has a 

 superficial ossification. The pubic cartilage in Cryptobranchus 

 is oblong, with a median process in front bearing the epipubis, 

 and the anterior angles of the oblong are slightly produced. 

 In Salamandra maculosa these angles form short broad pro- 

 cesses, which may be compared with the processus lateralis 

 pubis of Chelonia. 



We have, then, in reptiles two branches of the pubis — the 

 processus lateralis and the main body of the pubis — which 

 two branches it is possible to derive from the condition found 

 in Urodela. Also in Dinosaurs, Birds, and Mammals we have 

 the pectineal process and the main body of the pubis. The 

 splitting of the pubis into two branches is more complete — 

 i. e. it approaches nearer to the acetabulum — in the higher 

 forms. 



There is every probability that the two branches correspond 

 in some way in all these types. Two theories on the subject 

 are obviously possible. Either (1) the processus lateralis 

 of reptiles is the pectineal process of the pubis in Dinosaurs, 



