SECT. XI 



DEVELOPMENT 



159 



it may function both as directive and as visual organ. 

 Indeed, there is no reason why we should not assume 

 this double function at least during larval life, so long 



Fig. 37.— Naupllus of A . cancriformis just hatched (Glaus) from the side,_ showing 

 the unpaired " eye " in its passage from the ventral to the dorsal position. /, 

 large upper lip ; s, dorsal shield ; d, dorsal parapodium of the second antennae ; 

 c, sensory cirrus of the same. 



as the paired eyes are not developed, and the animal 

 is transparent. On the other hand, if it is a directive 

 body its disappearance in the higher Crustacea is 

 quite intelligible, especially in the Decapoda, which 



