172 A HISTORY OF RECENT CRUSTACEA 
the Porcellana and so institute a comparison. The zoea of 
Porcellana longicornis (see Plate VII.) has not unfrequently 
been studied, and the reality of its connection with the adult 
Fic. 15.—Porcellana longicornis (Linn.), an early post-larval form [Stebbing]. 
form need not be doubted, but the extraordinary difference 
between the one and the other can scarcely fail to surprise 
any one who for the first time compares them. It is 
strange that the smooth circular carapace of the grown-up 
Porcellana should result from a larval form in which the 
