IPHIMEDIA. 217 



A MPHIP ODA . P II OXIDES. 



NATATORIA. 



Genus— IPHIMEDIA. 



Iplumedia. Rathke, Beitr. zui- Faun. Nonvegens, Nov. Act. Leop. vol. xx. 



p. 89 (1843). Spence Bate, Ann. Nat. Hist. 2 ser. xix. 



p. 141, Feb. 1857. Cat. Crust. Amph. Brit. Mus. p. 123. 



White, Pop. Hist. Brit. Crust, p. 176 (not IpMmedia, Dana). 

 Microcheks. Keoyer, Tidsk. Nat. sec. 2, vol. ii. p. 5. 



Generic character. Cephalon produced autedorly. Pereion 

 distended. Pleon compressed. Eyes two. Antennae simple. 

 Third pair of siagonopoda not uuguiculate. First pair of gna- 

 thopoda feeble ; second also feeble, imperfectly subchelate. 

 Pereiopoda robust, having large and po^Yerful dactyla. Pos- 

 terior pair of pleopoda biramous. Telson single, squamous, 

 emarginate. 



In this genus the head is produced anteriorly. The 

 body is dorsally rounded and laterally distended, while 

 the tail is very rapidly narrowed. It is furnished with 

 a small eye upon each side of the head. The antennas 

 are subequal, and without a secondary appendage ; the 

 organs attendant upon the mouth are considerably pro- 

 jected forwards. The first pair of legs are feeble, and 

 have the fingers rudimentary ; the second are likewise 

 feeble, but terminate in an imperfectly chelate organ. 

 The coxae increase in depth to the fourth, which is 

 produced inferiorly to a sharp point. The last three 

 pairs of legs are tolerably strong, and terminate in 

 powerful fingers. The last pair of caudal appendages 

 are double-branched, and the telson is single, squami- 

 form, and emarginate. 



Our description differs from that of Rathke in a 



