neio Freshwater Gaminarid. 389 



Femarl-s. — I have given above the points that seem to 

 flistinf^ui.sii thi.s species from P. fra^/i/is. The fuilowing 

 fuller account is based on the single specimen before me : — 



Body rather shnder ; pleon-segments 4 to 6 with one or 

 two fine hair-like selas on dorsal surface, the fourth with a 

 stout spine on lower margin. Head without rostrum. First 

 antenna rather more than half as long as the body, first 

 joint with a tuft of small tactile setse on the upj)er margin 

 near the base, a few bair-like setae at the distal end, and a 

 small spine-like one on lower side of distal end ; second joint 

 about two thirds the length of first, with some slender setee 

 at extremity ; third joint about half as long as second ; 

 flagellum of about twenty joints, about twice as long as 

 peduncle; accessory flagellura of four joints. Second an- 

 tenna about two thirds as long as first; flagellum shorter than 

 peduncle. 



I have not examined the mouth-parts in detail, but they 

 appear to be closely similar to those of P.frajilis. 



First gnathopod smaller than the second ; carpus longer 

 than propod, suboblong, posterior margin densely fringed 

 with setae, a few on the anterior margin ; propod widening 

 towards distal end, where its width is about equal to its 

 length ; palm transverse, well defined, with a few small spine- 

 like setae and some long hairs ; dactyl rather st:)ut. Seco:ul 

 gnathopod with carpus short, triangular, produced on posterior 

 side into a rounded lobe bearing several fine setae ; propod 

 about twice as long as carpus, ovoid, narrowing distally, palm 

 very oblique, occupying two thirds length of posterior 

 margin, supplied with a double row of spine-like setae and a 

 few fine hairs ; dactyl rather stout, closely serrate on inner 

 margin. The third to fifth perajopoda moderately long, but 

 not greatly increasing in length posteriorly, the last reaching 

 as far as the end of pleon ; in each the second joint (basos) 

 is moderately broad, about two thirds as broad as long. 



First uropod with peduncle longer than the rami, its 

 upper margin with three small spines and a large one at 

 extremity; rami equal, each with a few spine-like setae; 

 second uropod similar, but with peduncle only as long as 

 rami ; third uropod extending much beyond the others, 

 peduncle only about one half as long as rami, which are equal, 

 not narrowing distally, and each with two groups of tiiree 

 spines and a terminal tuft of setae. Lobes of telson with the 

 posterior margin rounded and bearing two or three fine 

 liair:«. 



When alive the animal was, Mr. Crosby Smith savs, 



