[109] 



EMBRYOGRAPHY OF OSSEOUS FISHES. 



BGC, 



Fig. E, in longitudinal vertical section, represents, for instance, the 

 relations of the neurula 71 and the mesenteron e, showing them to be con- 

 tinuous by way of the solid caudal mass cm, in such forms as Alosa and 



•pfU 



Gadus. The dotted line nc can be regarded as indicating an open neural 

 canal only at the middle and anterior end of the body of the embryo; 

 nevertheless, the hinder end of the neurula, with the further growth of 

 the tail, actually acquires a lumen, as in Fig. K, but by this time the tail, 

 having gi-own out some distance, the continuity between the hind gut 

 e and caudal mass lias been torn asunder, and all that is left to mark 

 their original continuity is a strand of cells sf, shown in Figs. I and K. 

 This strand of cells was, however, only in part continuous with the gut, 



