316 



EDWIN S. GOODRICH. 



the only forms in which the pelvic girdles are thoroughly 

 well known are the Coelacanthidse and the Polypterid^.^ In 

 both these families the pelvic bones closely resemble those 

 of the Actinopterygii (Figs. G, L). 



Concerning the morphology of these pelvic supports there 

 is considerable confusion. Whilst the older anatomists be- 

 lieved them, I think quite rightly, to be homologous, and the 

 representatives of the pelvic girdle of other fish, some modern 

 authoi's would have us believe that they are of quite different 



YiG. F. — Ventral view of llie pelvic girdle and fins of Eusthenopt.eron 

 Foordi, Wliit., restored. 



nature in the various orders of Pisces. They hold that 

 whilst, for instance, in the Selachii, Holocephali, and Dipnoi, 

 a true pelvic girdle is present, the supports in the Crossop- 

 terygii and Actinopterygii are, on the contrary, derived from 

 the fin skeleton itself. 



Let us see what diflficulties such views lead us into. 

 Whether we hold, with the advocates of ihe fin-fold theory, 



1 Paired bony plates seem to have been present in Megalichthys (5, 9), and 

 Specimens 21,54-7 and P. 6513 of the British Museum Collection show traces 

 of similar structures in Osteolepis and Glyptolepis, 



