FJG. 290 



291 



PS M 



Figs. 290-295. Larval lung-fishes, Ceratodus. (After SEMON.) X 6. 290. 

 Embryo at about the time of hatching. 291. Young larva. 292. Larva of two weeks. 

 293. Larva of four weeks, ventral side. 294. Larva of six weeks. 295. Larva of ten 

 weeks. 



A. Anus. A U. Auditory vesicle. E G. External gills. GS. Gill slits. H. Heart. 

 M. Central nervous system. MC. Mucous canals. O. Opercular flap. OL. Olfac- 

 tory organ. PF. Pectoral fin. PN. Pronephros. PS. Primitive segments. S. Mouth 

 pit, stomodaeum. 



2I 9 



