1238 THE VOYAGE OF H.M.S. CHALLENGER. 



and in his third along with JEgina and JEginella. In the arrangement which Mayer 

 adopts for. his own work Caprellinoides might provisionally follow Caprellinopsis, but 

 the doubtfulness of the lower antennae and the uropods prevents any certain decision. 



Caprellinoides tristanensis, n. sp. (PI. CXLL). 



Body smooth, slender ; the rather skull-like head with the closely coalesced first 

 segment of the peraeon together shorter than the second segment of the perseon ; this 

 much shorter than the third, the third shorter than the fourth, the fourth about half the 

 length of the narrow and elongate fifth, the sixth not quite so long as the third, the 

 seventh not longer than broad ; the second segment is dilated anteriorly and narrow 

 distally, the third and fourth, as usual in the female (which sex alone was available for 

 investigation), much dilated, the third narrow for a very short space in front, the fourth 

 abruptly narrowed and tapering for the distal third of its length. The pleon has the 

 appearance, viewed laterally, of consisting of two very small joints, the second much 

 smaller than the first, but such an appearance is explained by Mayer 1 to be due to the 

 valve at the opening of the intestinal canal. 



Eyes not clearly made out. 



Upper Antennae. — First joint stouter than the second, but not so long ; second joint 

 twice as long as the third ; the third a little widened distally ; the flagellura longer than 

 the peduncle, of four elongate joints, the first as long as the second joint of the peduncle, 

 with two cylindrical filaments, each of the other joints with one such filament ; there are 

 a few setules or cilia on the peduncle as well as on the flagellum. 



Lower Antennas not much longer than the peduncle of the upper, the first two joints 

 very short, the gland-cone small, decurrent ; the third joint about as long as the coalesced 

 first and second ; the fourth joint longer than the three preceding united ; the fifth joint 

 rather longer than the fourth ; of the flagellum only two joints remaining, the second 

 considerably longer than the first, the appearance of its distal end indicating that a third 

 joint had probably been broken off. 



Upper Lip apically cleft. 



Mandibles. — The cutting plate divided into five teeth ; the secondary plate, at 

 least on one of the mandibles, nearly as broad as the primary, and likewise divided into 

 five teeth ; on this mandible a small prominence was visible, looking like a short 

 double-headed spine ; the first joint of the palp short, the second scarcely so long as 

 the third, with a setule near the middle of the inner margin, the third joint with five 

 slender spines on the oblique apical margin. Caprellinopsis longicollis (Nicolet) from 

 New Zealand has a somewhat similar palp, but with the second joint rather longer than 

 the third, carrying five setiform spines, the third joint having four unequal spines on 



1 Caprelliden, p. 95. 



