ORCIIKSTID^. 29 



somewhat shorter thjiii i)ropodos. Following pcreiopoda slender ; 

 the next two pairs sube(iual ; last two pairs subequal ; third pair 

 shortest ; setae of the margins of the propodos equal. 



" Fenmh.' — Propodos of second pair of gnathopoda minute, obovate, 

 oblong, rounded at apex ; dactylos lateral, longitudinal, its apex 

 rcadiing nearly to the extremity of the propodos. 



" Length, half an inch. 



*' Tongatabu, under sea-weed on beaches." — Dana. 



20. Orchestia tenuis. (Plate IV. fig. 10.) 



Urchestia tenuis, Ihina, Proc. Amer. Acad. Sci. ii. 202; U.S. Explor. 

 Exped. p. 872, pi. 50. f. 1. 



" Female. — Coxa3 rather narrow. Inferior antenna; slender, about 

 half as long as body ; flagellum very slender, much longer than 

 base ; joints oblong, setae hardly shorter than joints. Superior 

 antennae about as long as base of inferior. Gnathopoda quite small 

 and weak ; fii-st pau* much the smaller ; propodos of second pair 

 very smaU, oblong, bent backward, truncated half across towards 

 apex ; dactylos minute, rather remote from extremity, and nearly 

 transverse. First and second paii's of pereiopoda small ; the second 

 pair smaller than the fii'st ; three posterior pairs very unequal, in- 

 creasing regularly in length ; fifth pair nearly t'wice longer than 

 third; setae short, scarcely longer than diameter of joints. 



•' Length, half an inch. 



" Hah. Bay of Islands, New Zealand." — Dana. 



21. Orchestia nitida. (Plate V. fig. 1.) 



Orchestia nitida, Dana, U.S. Explor. Exped. p. 868, pi. 58. f. 5; Proc. 

 Amer. Acad. Sci. ii. 204. 



Coxae of moderate size, fifth smaller than fourth. Inferior antennae 

 shorter than half the body ; last two basal joints subequal ; fla- 

 gellum longer than base, moniliform, twelve- to fourteen-jointed; 

 joints slightly oblong, setae very minute. Superior antennae 

 about half as long as base of inferior, and flagellum five-jointed. 

 First pair of gnathopoda having a small propodos, slightly oblong, 

 .somewhat securiform, at apex somewhat broader and ol)liquely 

 truncate ; the carpus below near proi)odos gibbous. Propodos 

 of second pair large, subovate ; palm straight, nearly longitudinal ; 

 dactylos longer than half the propodos. Two anterior paire of 

 pereiopoda subequal, the rest gradually increasing i)i length, 

 rather sliort : .setic of propodos much sliorter than the semidia- 



