ON CRUSTACEA BROUGHT BY DR WILLEY FROM THE SOUTH SEAS. 665 



them having the lateral apices obliquely truncate between two acute points, the inner 

 of these overlapping the two following segments. The fifth thoracic segment is longer 

 than the fourth, and widens distally, bearing at its lateral apices the almost rudi- 

 mentary fifth feet. Near each lower corner of the genital segment there stands out 

 a seta, not regularly tapering, but divided as it were between lash and handle. 



First antennae. First two and last three joints short, the third nmch the longest, 

 all furnished with tapering setae, several of which are long. 



Second antennae. First two joints produced each subacutely over its successor, 

 third carrying three small setae, apical joint forming a strong hook. 



Mouth-parts. These appear to be degraded. All that I have been able to make out 

 clearly are first, a hook, having a broad base ornamented with very many close-set lines 

 running to the convex border, and a strongly curved very slender apex ; secondly, in 

 apparent attachment to this hook, a denticulate border lying across its base. I am 

 uncertain whether these parts together make up the mandible, or whether the sickle- 

 shaped portion is the mandible and the denticulate border the first maxilla. The second 

 maxillae and maxillipeds seem to be reduced to small plates with a few minute 

 spinules upon them. But in regard to these parts my dissections have not been 

 sufficiently skilful. 



Feet. In the first four pairs the outer ramus has the second joint shortest, a 

 single spine on the outer apex of this and of the first joint, two or three on the 

 outer margin of the third, whicli round the other margin carries several setae, the 

 second joint also having one very long seta on its hind margin ; the inner ramus 

 in the first three pairs, though not very long, is longer than the outer, and armed 

 in a similar fashion, but it has a seta on the hind margin of the first joint and 

 no spine on its front apex, two setae instead of only one on the second joint, and 

 on the other hand not so large a number of setae on the third joint as in the 

 outer ramus ; the inner ramus of the fourth pair consists of two slender joints, the 

 first carrying one seta, the second with one on its inner margin, but with two setae 

 on its oblique apex ; the slender fifth foot is, I think, certainly one-jointed, though 

 the pellucid overlapping corner of the thoracic segment may give the appearance of 

 an additional joint at the base ; it has an oblique apex, with a rather long seta at 

 the outer, and a short one at the inner point. Of the caudal setae, the longest 

 is about equal to the body minus the shield ; on its outer side is one which seems 

 to vary between half and two-thirds of its length, and external to this are two short 

 setae ; innermost of all are one or two more of great tenuity. Length, without caudal 

 setae, 1"25 mm., breadth, about '85 mm. The egg-sacs contain sometimes as many as 

 100 eggs a-piece. 



Male. Front of shield rather fiatteued, postero-lateral angles of this and the 

 following segment scarcely acute, and those of the second free segment rounded ; 

 the next segment very small, and the last scarcely defined from the gepital segment, 

 except by its projecting dietal angles; the genital segment with the sides parallel 

 instead of convex. First and second antennae and fifth feet and pei-haps the other 

 thoracic feet as in the female. The mouth-organs in the male seem to have become 

 aborted. The male and female in attachment, w'ith the shield of the male seeming 



