PELVKJ GIEDLE AND FIN OF EUSTHENOPTEllON. 



321 



the segmented axis of the fin of Ensthenopteion articulates 

 with the pelvic bone is strictly homologous with the corre- 

 sponding articulation at the base of the pelvic fin of Ceratodus 

 or Plenracanthus.^ We are, then, inevitably led to the con- 

 clusion that the pelvic supports, whether paired oi- unpaii-ed, 



Fig. K. — Ventral view of the peh-ic girdle and fins of Ceratodus Forsteri, 

 Kr. (Partly from Davidoff.) 



are homologous throughout the fish series. These structures 

 are similarly situated, fulfil the same functions, and are, as 

 far as we know, developed in the same way in all fish. In 



1 The persistence of tlie same articulation between the girdle and firi 

 skeleton is obvious in the case of tlie pectoral limb of fishes. 



