CHAP. VII. ZOE^E OF PORCELLANJE. 53 



It is further to be remarked that the Zoeae of the 

 crabs, as also of the Porcettanse, of the 

 Tatuira and of the Shrimps and Prawns, 

 are enveloped, on escaping from the 

 egg, by a membrane veiling the spinous 

 processes of the carapace, the setae of 

 the feet, and the antennae, and that 

 they cast this in a few hours. In 

 Aehasus I have observed that the tail 

 of this earliest larval skin resembles 

 that of the larvae of Shrimps and Prawns, 

 and the same appears to be the case in 

 Maia (see Bell, * Brit. Stalk-eyed Crust.,' 

 p. 44). 



Widely as they seem to differ from 

 them at the first glance, the Zoeae of 

 the Porcellan& (fig. 24) approach those 

 of the true Crabs very closely. The 

 antennae, organs of the mouth, and nata- 

 tory feet, exhibit the same structure. 

 But the tail bears five pairs of setae, and 

 the dorsal spine is wanting, whilst, on 

 the contrary, the frontal process and 

 the lateral spines are of extraordinary 

 length, and directed straight forward 

 and backward. 



The Zoea of the Tatuira (fig. 25) 

 also appears to differ but little from 



7 Fig. 24. Zoea of Porcettana stellicola, F. Mull. 

 Magn. 15 diam. 



