188 AMPniPODA NORMALIA. 



Oral appendages receding. Mandibles liaving au appendage. 

 Four anterior coxa; not so deep as thcia- respective segments ; three 

 posterior not mucli shorter than the preceding. Gnathopoda un- 

 equal ; second pair much the larger. Pereiopoda slender, subequal. 

 Posterior pair of plcopoda biramous, subfoliaccous. Telson double. 



This description is taken from a recent specimen of the same species 

 as that from which Leach drew up his characters. It differs from 

 Dana's description, which is so characteiized as to exclude Leach's 

 t}ye. It is to be regretted that Dr. Leach, who had such an intuitive 

 perception of generic arrangement, should Lave so imperfectly de- 

 scribed species. 



1. Mcera grossimanus. (Plate XXXIV. fig. 3.) 



Cancer (Gammarus) grossimanus, 3Iontagu, Litm. Tram. ix. t. 4. f. 5. 

 Mrera grossimanus, Leach, Edinb. Enctjc. vii. p. 403 ; Linn. Trans, xi. 

 p. 359. 



Destnaresf, Consid. stir les Ch-tist. p. 265. 

 Gammanis grossimanus, Edio. Hist, des Crust, iii. p. 54. 



JJlute, Cat. JB. M. Crust. 1847 ; Cat. Brit. Crust. B. M. 1849 ; 



Hist. Brit. Crust, p. 185. 

 Gosse, Marine Zool. i. p. 141. 



Spence Bate, Synopsis, ^-c., Ann. Nat. Hist. Feb. 1857. 

 Ganuuarus Impostii, Edwards, Ann. des Sci. Nat. xx. p. 368 ; Hist des 

 Crust, iii. p. 49. 



Cephalon long, nearly as long as the fii'st three segments of the 

 pereion. Pereion as long as the pleon ; second segment having 

 the inferior margin ciliated with five or six equidistant hau-s, and 

 convexly produced below the infero-posterior angle. Third segment 

 of the pleon having the infero-posterior angle produced to a point. 

 Eyes subreniform, black. Superior antennae nearly half as long 

 as the animal, having the fii-st joint of the peduncle as long as the 

 cephalon, the second half as long again as the fii-st, the third 

 short; flagellum about the length of the second joint of the 

 peduncle; secondary appendage half as long as the primary. 

 Inferior antennce not so long as the peduncle of the superior; 

 pedimcle having the last joint shorter than the preceding ; flagellum 

 not longer than the last joint of the peduncle. First pair of 

 gnathopoda ha-\Tng the upper distal angle of the carpus produced 

 to a point ; propodos of moderate size, ovate ; palm convex, oblique, 

 not well defined. Second pair of gnathopoda much longer than 

 the first, having the meros iaferiorly and distally produced to a 

 sharp point ; carpus very short, suddenly enlarging to almost the 

 diameter of the propodos, inferior angle produced to a point ; pro- 

 podos very large, as long as the cephalon and the first two segments 

 of the pereion, and rather more than half as broad as long ; in- 



