REPORT ON THE ISOPODA. 17 



Each of the three succeeding segments has a pair of lateral spines on either side, the 

 anterior being much the longer and curved ; in the remaining segments of the thorax 

 only the anterior spine is present, the posterior having become obsolete. The length of 

 the lateral spines increases slightly in the successive segments, being therefore longer in 

 the seventh segment of the thorax than in any of the others. 



The spines upon the thorax do not correspond to the epimera, which are very small 

 and He beneath them ; in the three posterior segments the epimera are each furnished 

 with a minute spine. 



The segments of the abdomen are fused into a single piece which is almost circular in 

 form ; on either side are three spines much shorter than the lateral spines of the thorax ; 

 and on either side of the blunt termination of the abdominal shield are two minute 

 tubercles, between which the uropoda are articulated. 



The antennules (PL IV. fig. 10) are rather less than half the length of the antennae; 

 they measure about 6 mm. 



The basal joint is stout and short and somewhat curved ; the second is the longest 

 and is much more slender ; the third and fourth are very short, the fourth (PI. V. fig. 3) 

 being extremely minute. The flagellum is about as long as the three distal joints of 

 the peduncle ; it is composed of twenty -four joints, the first being very long, and about 

 equal to the next four. 



The antennae (PI. V. fig. 2) measure 13 mm. in length; the flagellum is nearly as 

 long as the peduncle. The two basal joints of the peduncle are very short ; the second 

 has a long, spiny process on the outer side ; the third is rather longer and has a long 

 spine which differs from that upon the second in being articulated ; it probably corre- 

 sponds to a rudimentary exopodite ; the fourth joint of the peduncle is very much shorter 

 again, while the two distal joints are elongated and enlarged. 



The mandibles are provided with a palp. 



The first pair of rnaxillse are shown in fig. 1 of PI. V.; there is nothing remarkable in 

 the form of these appendages. 



The second pair of maxillss are shown in fig. 4 of the same plate. 



The apex of the larger lobe is furnished with four or five stout serrate spines, the middle 

 lobe having three long spines, and the third lobe also three such spines which are not serrate. 



The maxilli'pedes (PL IV. fig. 11) have a very long and straight stipes ; just opposite 

 to the articulation of the palp are five or six sensory processes. The palp is five-jointed ; 

 the second joint is the widest and at the same time the longest ; the terminal joints are 

 short and narrow. 



The thoracic ap2^endages are all similar to each other and terminate in two claws 

 (PL IV. fig. 1 2) as in allied genera. 



The specimen being a female, the abdominal appendages are covered by a large 

 operculum which is traversed by three longitudinal ridges, one median and two lateral. 



(ZOOL. CHALL. EXP. — PART XLVIII. — 1886.) Bbb 3 



