XVI 



The homologies of the elements of the shoulder girdle of the Dipnoi 

 appear then to be as follows : — 



THE GIRDLE IN OTHER FISHES. 



Proceeding from the basis now obtained, a comparative examination of 

 other types of Fishes successively removed by their affinities from the 

 Lepidosirenids may be instituted. 



I. 



With the humerus of the Dipnoans, the element in the Polypterids 

 (single at the base but immediately divaricating, and with its limbs bor- 

 dering an intervening cartilage which supports the pectoral and its basilar 

 ossicles) must be homologous. 



But it is evident that the external elements of the so-called carpus of ^ 

 teleosteoid Ganoids are homologous with that element in Polypterids. 



Therefore, those elements cannot be carpal, but must represent the 

 humerus. 



1 Gelenkstelle der Brustflosse am primiiren Schulterknorpel. — Gegenbaur. 



2 Clavicula. — Gegenbaur. 



3 Verbindungsstelle des beiderseitigen Scbulterknorpels. — Gegenbaur. 



Prof. Gegenbaur regards tbe median cartilage as a dismemberment of a common 

 cartilage, tbe upper division of wbicb receives tbe pectoral limb, wbile tbe lower 

 unites witb tbe corresponding dismemberment of tbe opposite side anil forms tbe 

 median cartilage. 



4 The suture separating tbe "coracoid" into two portions has been observed by 

 Dr. Giinther, but he could "not attach much importance to this division." 



