XVII 



II. 



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

 is articulated must be homologous with the analogous element in Dipnoans, 

 and therefore with the Coracoid. 



The Coracoid of Polyptcrids 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 Cora- 

 coid element of the Ganoids represents the three elements developed in the 

 generalized 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 maybe named Hypercoracoid ; the lower, 

 IIypocoracoid ; and the transverse or median, Mesocoracoid. 



Ill— IY. 



(Proscapula, or united Scapula and Ectocoracoid.) 

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

 clavicle" (= scapula), and "clavicle" (= ectocoracoid) seem to be com- 

 parable together, and as a whole with the single element carrying the 

 humerus and pectoral fin in the Crossopterygians (Polypterus and Cala- 

 mmcMhys) and other fishes, 1 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 ectocoracoid fused 

 together, has received no name which is not ambiguous or deceptive in its 

 homological allusions, it may be designated as Proscapula. 



Y. 



The posttemporal of the Dipnoans is evidently represented by the anal- 

 ogous element in the Ganoids generally, as well as in the typical fishes. 



The succeeding elements (outside those already alluded to) appear from 

 their relations to be developed from or in connection with the posttem- 

 poral, and not from the true scapular apparatus ; they may therefore be 

 named Posttemporal, Posterotemporal, and Teleotemporals. 



1 Dr. Gunther (Phil. Trans., v. 161, p. 531) has observed, respecting the division 

 in question in Lepidosiren and Ceratodus : " I cannot attach much value to this divi- 

 sion ; the upper piece is certainly not homologous with the scapula of Teleostean 

 fishes, which is far removed from the region of the pectoral condyle." 



October, 1872. 2 



