Morphology of the Fins 



89 



so-called carpus of the teleosteoid Ganoids are homologous 

 with that element in Polypterids. Therefore those elements 

 cannot be carpal, but must represent the humerus. 



" The element with which the homologue of the humerus, in 

 Polypterids, is articulated must be homologous with the anal- 

 ogous element in Dipnoans, and therefore with the coracoid. 

 The coracoid of Poh^pterids is also evidently homologous with 

 the corresponding element in the other Ganoids, and the latter 

 consequently must be also coracoid. It is equally evident, 

 after a detailed comparison, that the single coracoid element of 

 the Ganoids represents the three elements developed in the gen- 

 eralized Teleosts (Cyprinids, etc.) in connection with the basis 

 of the pectoral fin, and, such being the case, the nomenclature 

 should correspond. Therefore the upper element may be named 



Fig. 75. — Shoulder-girdle of a Threadfin, Pohjdadylus approximans (Lay and 



Bennett). 



hypercoracoid; the lower, hypocoracoid; and the transverse or 

 median, mesocoracoid. 



" The two elements of the arch named by Parker, in Lepidosi- 

 ren, ' supraclavicle ' (scapula) and 'clavicle' (ectocoracoid) seem 

 to be comparable together, and as a whole, with the single 

 element carrying the humerus and pectoral fin in the Crossop- 

 terygians {Polypterus and Calamoichthys) and other fishes, and 

 therefore not identical respectively with the 'supraclavicle' 

 and ' clavicle ' (except in part) recognized by him in other fishes. 

 As this compound bone, composed of the scapula and ectocora- 

 coid fused together, has received no name which is not ambig- 



