62 



or giilar plate of Ainia. This, however, is so very 

 problematical that to prevent confusion, Cunningham's 

 term must be rejected. 



12. — Pelvic Girdle and Fin (Fig. 9). 



Innominate or Pubic Bone {In.). — Situated just 

 behind the ventral extremity of the clavicle. It is 

 strongly connected by its dorsal extremity with the inner 

 face of the clavicle opposite the upper boundary of the 

 clavicular symphysis. It is also connected more or less 

 for the whole of its length, and especially ventrally, with 

 the innominate of the other side. In medium-sized plaice 

 it consists of three pieces, but the tendency is for the lower 

 extremity to calcify. The dorsal piece (1) is the largest 

 and consists of a fairly strong posterior rod, produced 

 below into a ventral spine, to which is attached in front a 

 thin bony plate. Ventrally there is an obvious piece of 

 cartilage (2) which gives attachment to a terminal car- 

 tilaginous epiphysis (3), which in its turn supplies the 

 surface over which works the sub-cartilaginous pad giving 

 articulation to the fin rays. 



Fin Rays (F.R.). — Articulate directly with the 

 innominate except for the intervention of a sub-car- 

 tilaginous pad as in the case of the pectoral fin. The fin 

 rays here resemble those of the pectoral fin, and consist 

 each of two pieces, but the latter diverge more proximally, 

 and the posterior articular processes are terminal instead 

 of sub-terminal as in the pectoral fin. The fourth and 

 fifth of these processes, further, projected backwards and 

 downwards instead of straight backwards as with the 

 others (cp. fig.). None of the fin rays bifurcated, and 

 there were the normal six of them in the pelvic fin of the 

 specimen now described. 



