GAMMAniD.'E. 225 



tho superior. Gnathopoda subcholate, the seconrl pair being tlie 

 larger. Posterior pair of pleopoda birumoiLS. TeLsoii double. 



Tliis genus is distinguished from ^fly)•a by the relative size of the 

 second pair of gnathopoda, by the greater depth of the coxa), and by 

 the more compact fonu of the animal generally ; and from Oammarus 

 by tho absence of the fasciculi of spines upon the dorsal surface of 

 the caudal segm.ents and the shortness of the inferior antennae. It 

 is included by most authors in the genus Gammaru.t, but distin- 

 guished as a group by itself. 



1. Megamcera dentata. (Plate XXXIX. fig. 4.) B.M. 



Ganimarus deiitatus, Kroi/cr, Nat. Tichkr. iv. p. 159. 



Bnizdiiis, Skand. Ainph. Gdmni. p. 61. 

 Gammai'us purpuratus, Stimpsou, Marine Invertebrata Grand 3Iayian, 

 p. 55. 



Pleon having the posterior margin of each segment serrated upon 

 the dorsal surface. Eyes round, black. Superior antenna; longer 

 than, the body of the animal ; first two joints of tho peduncle sub- 

 equal, third short ; flagellum as long again as the peduncle ; 

 secondary appendage short. Inferior antennae half as long as the 

 superior ; peduncle longer than the peduncle of the superior ; fla- 

 gellum as long as the last joint of the peduncle. First pair of 

 gnathopoda small, having the carpus as long as the propodos : 

 second pair larger than the first, having the carpus short and con- 

 tinuous with the propodos ; propodos obHquelj" quadrate, rather 

 longer than broad, infeiior margin nearly parallel with the supe- 

 rior, thickly ciliated ; palm slightly oblique, defined by a blunt 

 tooth. Pereiopoda subequal. Posterior pair of pleopoda longer 

 than the preceding, having one long and one rudimentary ramus. 

 Tclson double. 



Length ^ths of an inch. 



Hah. Greenland, in 40 to 50 fiithoms {HolhoU). 



" Taken oft' a sandy bottom, in 12 fathoms, off" Cheney's Head, 

 Grand Munan. It also occurs in deep water in Massachusetts 

 Bay. The colour never varies, being a uniform dark purple." — 

 Sthnpson. 



It is not without careful consideration that I have included Gam- 

 iiiarus imrpuratus of Stimpson in the present species. The description 

 and figure in this Catalogue are taken from specimens presented to the 

 British Museum by M. Holbijll, from whom Kroyer also received the 

 type. Those in the British Museum had no name attached, but they 

 agree with KnJyer's description, which only diHei-s IVoni (jr.purpuratuR 

 in having teeth upon the posterior margin of the first segment of the 

 pl(?on. 



a 



