DESCRIPTION OF SPECIES 34i 



The abdomen consists of three free segments and a large terminal one. Each of the 

 first three is slightly keeled and bears a small spiniform process corresponding in position 

 with those of the thoracic somites ; the pleural plates of the second and third abdominal 

 segments are well developed, but do not extend backwards quite so far as the coxal 

 plates of the seventh thoracic somite ; those of the third segment are slightly the longer. 

 Each of the sternal plates of these segments has the median posterior border produced 

 into a spine, increasing in length from the first to the third. 



The terminal segment (Fig. i6) is roughly triangular in shape, with the apex directed 

 backwards and with the basal angles broadly rounded. On its dorsal surface is a strong 

 median carina which extends to the end of the upturned posterior extremity ; this carina 

 is broadest anteriorly where there is a small oval pit in a median position on its dorsal 

 surface. Two pairs of lateral carinae are also present ; one on either side runs parallel 

 with the lateral margin of the segment but a short distance within it; the other lies 

 almost midway between the latter and the median carina, with which it runs almost 

 parallel, meeting the outer lateral carina at a point level with the posterior end of the 

 coxal plate of the seventh thoracic somite. 



The antennule is short and consists of a peduncle of four joints, and a flagellum, 

 which in the male comprises ten joints, in the female seven. The first peduncular joint 

 is not much longer than broad ; the second is about the same length with its postero- 

 distal angle slightly produced ; the third joint is more than twice as long as the second, 

 broad proximally, but narrowing distally ; the fourth is about half the length of the third. 

 The flagellum is not quite as long as the third peduncular joint ; its joints, except for the 

 terminal one, which is minute, are all of approximately the same size : the third to the 

 tenth each bear a sensory seta of the usual type, placed near the anterior distal angle. 



The antenna is nearly twice as long as the antennule: both the peduncle and the 

 flagellum consist of five joints. The first joint of the peduncle is short, broader than long; 

 the second is about three times the length of the first, with its anterior distal angle pro- 

 duced, and with the proximal part of the anterior margin covered with short hairs; in 

 the third peduncular joint the anterior margin is equal in length to that of the second 

 joint, but with its posterior margin curved, and considerably shorter; this joint is 

 broadest distally, has its anterior distal angle somewhat produced, and short hairs are 

 present on its posterior margin. The fourth peduncular joint is twice the length of the 

 third, with a dorsal longitudinal ridge extending along its upper surface near the 

 posterior margin; the fifth joint is nearly twice as long as the fourth but considerably 

 narrower. On the ventral surfaces of the third, fourth, and fifth joints is a series of 

 short transverse rows of setae which are arranged in bundles ; each bundle consists of 

 about five long dehcate setae arising from a common basal "knob", and the transverse 

 rows, each of which contains three or four of these bundles, extend from about the 

 middle of the ventral surface as far as the anterior margin. There are two transverse 

 rows on the third, five on the fourth and seven on the fifth joint. 



The mandibles are built on the usual plan and their cutting edges are comparatively 

 simple ; that of the right mandible is divided into four by three shallow notches, with 



