ITS STRUCTURE, BULK, AND ASPECT. 93 



mammals we find exemplified in but the scapulars. It seems, 

 like these, to have furnished the base to which some suite of 

 moveable bones was articulated, — in all likelihood that pro- 

 portion of the carpal bonelets of the pectoral fins which are 

 attached, in the osseous fishes, to its apparent homologue the 

 radius. Fig. e, a slim light bone, which narrows and thickens 

 in the centre, and flattens and broadens at each end, was pro- 

 bably a scapula or shoulder-blade, — a bone which in most 

 fishes splices on, as a sailor would say, by squamose jointings 

 to the coracoidian bone at the one end, and the super-scapu- 

 lar bone at the other. As indicated by its size, it must have 

 belonged to a small individual : it is, however, twice as long, 

 and about six times as bulky, as the scapula of a large cod. 

 Of the bone represented in fig. 48, I have determined, 

 from a Cromarty specimen, the place and use : it formed the 



Fig. 48. 



ISCHIUM OF ASTEROLEPIS. 



(One-half nat. size, linear.) 



interior base to which one of the ventral fins was attached. 

 In all fishes the bones of the hinder extremities are inade- 

 quately represented : in none do we find the pelvic arch com- 

 plete ; and to that nether portion of it which we do find re- 

 presented, and which Professor Owen regards as the homo- 

 logue of the OS ischium or hip-bone, the homologues of the 

 metatarsal and toe-bones are attached, to the exclusion of the 

 bones of the thigh and leg. In the Abdominales, — fishes such 

 as the salmon and carp, — ^that have the ventrals placed behind 

 the abdomen, in the position analogous to that in which the 



