[109] 



EMBRYOGRAPHY OF OSSEOUS FISHES. 



563 



Fig. E, iu loiigitiidinal vertical section, represents, for instance, the 

 relations of the nenrula n and the mesenteron e, showing them to be con- 

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



A 



■/»«. 



Gadus. The dotted line ne 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 farther growth of 

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

 having grown out some distance, the continuity between the hind gut 

 e and caudal mass has been torn asnnder, 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, 



