264 



CRUSTACEA. 



the Protozoaea stage of this genus. More recently, many larval forms belonging 

 to this series have been described from the Challenger material (Spence Bate 

 No. 100). 



The youngest Protozoaea of Sergcstes is only known from a drawing b] 

 Willemoes-Suhm (No. 100, p. 354). It possesses the seven anterior pairs o 

 limbs, but the third pair of maxillipedes has not yet developed. Only the firs 



PlO. 121.— Two larval stages of Sergestes (after Claus). A, Protozoaea stage. B, Acanthotom 

 stage, seen from the dorsal side, a', first antenna ; a", second antenna ; mf, tirstmaxillipede 

 mj", second maxillipede; ?»/'", third niaxillipede ; mx\ first maxilla; mx" y second maxilla 

 ol, upper lip ; sd, shell-gland. 



rudiments of the paired eyes can be made out. Within the alimentary canal a 

 large amount of yolk remains, und this no doubt allows the larva to leave the 

 egg at this stage. In all other respects the larva drawn by Willemoes-Siiim 

 agrees with the youngest stage described by Claus (Fig. 121 A). 



This latter (Fig. 121 A) can be compared in all its essentials with the later 



