170 HISTORY OF THE HUMAN BODY 



The fault in the above theory is that, while offering a direct 

 transition from the selachian to the amphibian form, it leaves 



FIG. 44. Series illustrating a theory of the phylogenetic development 

 of the pelvic girdle. [Mainly after WIEDERSHEIM.] 



(a) Acipenser (sturgeon), (b) Scaphyrhynchus (shovel-nosed ganoid), (c) Polyp- 

 terus (ganoid). (<i) Necturus (primitive salamander). (e) Dactylethra (South 

 African frog), (f) Turtle. 



In (a) the part m is formed by a fusion of the anterior rays. The pieces kk, 

 segmented off from m in (b), form in (c) a rhomboidal plate. In (d) this plate 

 has grown large and bears a pair of ossified ilia, i, and a pair of centers of ossi- 

 fication, the ischia, h. In (g) appear two more ossific centers, the pubes, g. (f) 

 is a typical pelvic girdle, with all its parts. The epipubis, e in (e), is incidental 

 and unimportant in this connection. 



no solution for the various conditions that occur in ganoids, 

 some of which, at least, ought to be included in the line of 

 descent. For these a plausible solution is offered in Fig. 44, 



