1364 THE VOYAGE OF H.M.S. CHALLENGER. 



apical tooth ; the second joint not longer than broad, with a front apical tooth ; the 

 third joint narrower than the second, not twice as long ; the fourth slightly curved, more 

 than twice as long as the second ; the fifth slender, nearly twice as long as the third ; 

 distally armed as in the first and second pairs ; the front margin of the third, fourth, and 

 fifth joints scabrous ; the finger minute, bulbous at the base. 



Fifth Perasopods similar to the fourth, but with different relative proportions, the 

 first joint being rather longer than in the preceding pair, considerably longer than all 

 the following joints together, all of which are inferior both in length and breadth to the 

 corresponding joints in the fourth perasopods, so that in total length these limbs are the 

 shortest of the perajopods, though longer than the gnathopods. Arranged in gradation 

 according to length, the order of the limbs would be gn.l., gn.2., prp.5., prpA., 

 prp.?>., prp.2., prp.l. 



Pleopods. — Peduncles broadly oval, as usual the second pair shorter than the first 

 and the third than the second ; the coupling spines short and tolerably stout, the apex 

 acute, with a pair of retroverted teeth, below which a second pah' are placed, one tooth 

 occupying each margin ; in the first pair of pleopods there are three coupling spines ; 

 the cleft spine having the arm with the expanded apex rather the shorter ; the rami 

 shorter than the peduncles, with six or seven joints to the inner, and seven or eight to 

 the outer ramus. 



Uropods. — The peduncles narrow, longer than the rami, smooth edged ; the rami 

 narrowly lanceolate, the outer finely pectinate on the inner margin, the inner on the 

 outer margin ; in the first pair the peduncles slightly longer and narrower than 

 those of the third pair, the outer ramus scarcely longer than the inner ; the two rami 

 slightly apart at their bases ; the peduncles of the second pair much narrower than those 

 of the first, and a little more than half the length, the outer ramus being also much shorter 

 and narrower than the rami of the other pairs, the inner ramus represented only by a 

 produced rather blunt tooth or process of the peduncle ; the rami of the third pair almost 

 equal, the outer perhaps a little the longer. 



Telson nearly semicircular, of extreme tenuity, and therefore very difficult to perceive, 

 especially as, owing to its very small size, it does not project beyond the divided margin 

 of the ventral opening. 



Length. — In a straight line from the front of the head to the extremity of the uropods, 

 the specimen measured, in the position figured, three-tenths of an inch. 



Female. — The seventh segment of the perason more elongated than in the male and 

 the dorsal emargination of the distal end more conspicuous ; the first three segments of 

 the pleon more elongate in proportion to their depth and differently shaped, widening a 

 little distally, with the postero-lateral angles sharply produced into pronounced teeth, 

 another little tooth standing a little higher up on the hind margin, this tooth being 



