iivri;Kii).E. 31 1 



'. CYSTOSOMA. 



Cystosoniii, (itienn-McnevilU', Revue Zuuhxjiqiie, i. p. 214, July 1842 

 (nut Ifcxticoo;!). 



Ccphulou large, anteriorly depressed. Eyes occupying nearly the 

 entire cephalon. Superior antenna absent. Inferior antenna; 

 short, slender. Gnathoi)oda small, having the carpi inferiorly 

 l)rodufod. First pair of pereiopoda much longer than the gnatho- 

 poda ; second pair longer than the first ; third pair much longer 

 than the second ; fourth pair shorter than the third, and fil'th 

 pair much shorter than the fourth. Three posterior pairs of pleo- 

 poda long, slender, terminating in short lanceolate rami. Telson 

 single, squamose. 



1. Cystosoma Neptuni. (Plate L. fig. 7.) 

 Cystosoma Neptuni, Gu4rin-Meneville, Revue Zooloyique, July 1842. 



Cephalon having the anterior margin furnished %vith a submarginal 

 row of minute denticles. Pereion and pleon corrugated and im- 

 bricated. Gnathopoda very minute, subequal. Pii'st pair of 

 pereiopoda very slender, nearly four times as long as the gnatho- 

 poda, having the basos posteriorly serrated, as also the posterior 

 margin of the meros and carpus ; propodos as long as the carpus, 

 but not so stout, unarmed ; dactylos short : second pair like the 

 first, but longer : thii'd paii- very long, having the anterior margin 

 of the basos serrated ; meros and cai-pus continuous, straight, 

 having the anterior margin serrated; propodos much narrower 

 than the carpus, straight, unarmed ; dactylos minute : fourth pair 

 like the third, but shorter: fifth like the preceding, but much 

 shorter, and not so distinctly serrated. Pleopoda long, slender, 

 reaching to about the same length ; rami short, lanceolate. Telson 

 naiTow, tapering, sharp, nearly as long as the peduncle of the 

 ultimate pair of pleopoda. 



Length 34 inches. 



Uab. Indian Ocean (Ouerin-Meneville). 



8. THEMISTO. 



Themi.sto, Guerin-Mencville, Mim. de la Sue. d'llist. Nat. de Paris, iv., 

 1828. 

 Edwards, Ann. des Sc. Nat. xx. p. 39o ; Hist, des Crust, iii. p. 84. 



Cephalon transversely ovate. Pereion not largely distended. Picon 

 slendi-r. Eyes occupying the entire cephalon, doi-sally separated. 

 Antennae subequal, ;is long as the cephalon is deep ; superior pair 

 liaving the flagelhim not articiilated : inferior pair having the 



