220 AMIMlllMMIV NOKMAI.IA. 



2iJ. Gammarus Pugetteasis. (I'i^ate XXXIX. fig. 3.) 



Gamniarus rugctteiisis, Dana, U. S. Explor. Exped. p. 957. pi. 60. f. 1. 

 Stimpson, Journ. Host. Soc. Nat. Hint. vi. 



*' Coxae large, fifth much sliortcr than fourth. Fourth segment of pleon 

 acute above. Superior antenna) much shorter and more slender 

 than inferior; second joint of base shorter than first; flagellum 

 nearly twenty-articulated, almost naked ; secondary appendage 

 short, five- to six-articulated. Inferior antennaj quite stout, not 

 half as long as body ; base long, nearly naked, last two joints sul)- 

 equal ; fiagellum a little longer than preceding joint, about ten- 

 articulated, articuli not oblong. Gnathopoda rather small ; pro- 

 poda subequal, each being broad for its length, partly short-hirsute 

 below, apex obliquely truncate, palm a little excavate, lower angle 

 rounded ; dactylos not longer than palm. Fourth and fifth pairs of 

 pereiopoda subequal ; setae few, short. Posterior pair of pleopoda 

 quite long, projecting muclj^ beyond the second ; outer branch vei-y 

 stout and bearing some very short si)inules, the inner more slender 

 and pilose. 



" Length of body 9 lines. 



'^ Bab. Puget's Sound, Western America." — Dana. 



30. Gammarus tenuicornis. 



Gammarus tenuicornis, Stinqjson, Proc. Acad. Nat. Sci. Philad. May 

 and June 1855. 



" Compressed. Posterior segments of the pleon with two or thi-ee 

 short setae on the dorsal surface. Superior antennae as long 

 as the body, with a 22-articulate flagellum ; secondary appendage 

 triarticulate. Eyes small, cii'cular. Second pair of gnathopoda the 

 larger. Fourth and fifth pairs of pleopoda having slender, smooth 

 rami ; posterior pair with the external ramus long, thick, styli- 

 form, setose, the internal one extremely minute. Telson of con- 

 siderable length, curved, each division surmounted by a long spi- 

 nule. Colour blacldsh olive. 



" Length ird of an inch. 



''Hub. Loo Choo." — Stim^json. 



31. Gammarus rubro-maculatus. 



Gammarus rubro-maculatus, Stimpson, Proc. Acad. Nat. Sci. Philad. 

 July 1856. 



" Rather large : spotted with crimson above, white below. Eyes 



subovate. Superior antennae half as long as the body ; inferior 



ones much shorter and more slender. First pair of gnathopoda 



very small and weak ; second pair large, compressed, and with a 



sharp spine at the middle of the lower edge, where the dactylos 



I 



