320 M. Ussows; Zoologico-Emhryoloyiciil Investigations. 



To show tlio part taken by tlie different germ-lamellae in 

 the formation of the various organs, I add the following 

 Table :— 



Comparing the development of the three Deeapoda investi- 

 gated by me with that of the single Octopod to which I had 

 access, I find a great agreement betwec^n them, but with the 

 exception that the primitive groove which I have described 

 in the case of the Deeapoda does not close in Argonauta. 

 In the time and the mode of appearance of the principal 

 organs (alimentary apparafu.s, central nervous system, circu- 

 latory organs, &c.) in the embryos of the two groups they 

 perfectly correspond. 



The unimportant fact of the late appearance of the yelk- 

 sac in f^epia, already remarked by Kolliker*, is the sole 

 peculiarity of that genus that is not reproduced in the other 



Deeapoda. 



* Loc. cit. p. <>0. 



