558 CRUSTACEA. 



as the claw, and they may be separated at will, like fingers. Palpus 

 of these legs has the basal joint nearly or quite as broad as long, 

 narrowest below, and rounded at apex, excepting in first pair, in which 

 it is subacute on the more prominent side. Posterior legs shorter 

 than the five pairs preceding. At base of last pair in a female, a pair 

 of large lunate, concave plates, as in Mysis, forming together a pouch, 

 within which the immature young are confined. 



Within the thorax, extending through three or four segments pre- 

 ceding the last, there is a pair of oblong glandular masses, of a deep 

 blue colour, pearly by reflected light. They are very large, and 

 occupy more than half the length of the thorax. The stomach was 

 just anterior to these glands; it was membranous, and in folds above. 

 The liver was situated above the stomach, as appeared through the 

 shell. 



First five segments of abdomen subequal, together about as long as 

 the carapax ; sixth segment as long as fourth arid fifth ; seventh seg- 

 ment a little shorter than sixth, narrowing a little to a rounded entire 

 apex, which is furnished with a few short spines, and another series of 

 still shorter spines. Caudal lamellae longer than segment, the outer 

 but slightly longer and furnished within with hairs as long as the 

 lamella; the inner much longer but not ciliate, both rounded at apex. 



These animals move with rapidity and very gracefully. 



SlRIELLA GRACILIS. 



Carapax fronte paulo triangulatus. Segmentum abdominis posticum 

 spinulis circumdatum, spinulis duabns longioribus, lamina caudali 

 externd paulo brevius et interna multo brevius. Oculi mediocres. 

 Flagella antennarum internarum valde incequa, majore longitudine 

 thoracem superante; externarum flagellum dimidio corporis longius. 

 Pedum rami thoracicorum incequi. 



Carapax low triangulate in front. Last abdominal segment edged 

 with spinules, two spinules longer than the rest, length, a little less 

 than that of outer caudal lamina, much less than that of the inner. 

 Eyes rather small. Flagella of inner antennas very unequal, the 

 larger longer than thorax. Flagellum of outer antennae two-thirds 

 as long as the body. Branches of feet unequal. 



