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



Pleon having the five anterior somites subequal. The first two dorsally smooth ; the 

 three succeeding armed with a strong tooth on the posterior dorsal region. Sixth somite 

 about the length of the two preceding combined, and with the postero-dorsal angle pro- 

 duced to an obtuse point. 



Telson about half the length of the sixth somite. 



Ophthalmopoda about two-thirds the length of the carapace, fungiform in appearance; 

 ophthalmus broad, stalk narrow. 



First pair of antennae having the peduncle a little longer than the ophthalmopoda; 

 first joint longest, second and third subequal, supporting a long and slender flagellum 

 that is quite the length of the animal, and has a bulbous enlargement at the base, from 

 which there usually springs a fasciculus of membranous cilia. 



The second pair of antennae support a similarly formed but rather longer, flagellum, 

 and a scaphocerite that is equal in length to the peduncle of the first pair. It has the 

 inner and outer margins subparallel, the outer being smooth and armed with a strong 

 tootli near the distal extremitv ; the inner maroin foliaceous and fringed with a thick row 

 of ciliated hairs. 



The first pair of gnathopoda possesses no specific character. 



The second is long, robust at the base and slender towards the distal extremity, 

 where it is fringed with hairs disposed in pairs, one on each side, the hairs supported on 

 strong prominences, each alternately larger and smaller ; the distal extremity is tipped 

 with three long, strong, simple hairs. 



The first pair of pereiopoda is about half the length of the second pair of gnathopoda; 

 it is slender and feeble and carries a small prehensile organ. The second and third pairs 

 are long and slender, and terminate in a small chela, the extremity of each digit being- 

 tipped with a small brush of hairs ; the third pair has the fingers longer and more 

 slender than the second. The fourth pair is short and very slender, reaching nearly to 

 the distal extremity of the. ischium of the third pair. The fifth or terminal pair is very 

 much shorter than the fourth, and is rudimentary in character. 



The pleopoda are slender but not long. The first pair is the most slender, and is 

 single-branched ; the others are biramose and become gradually shorter posteriorly ; the 

 posterior pair, which helps to form the rhipidura, has the outer and longer plate armed on 

 the external margin with a strong tooth about midway between the base and the distal ex- 

 tremity, and the margin beyond is fringed with long ciliated hairs, as also is the inner plate. 



Length, 12 mm. (0'5 in.). 



Habitat. — West Pacific Ocean. 



Station 354, May 6, 1876; lat. 32° 41' N., long. 3(5° 6' W.; Mid North Atlantic; 

 surface temperature, 70° '0. 



Observations. — A specimen (Pi. LXVII. fig. 2) very similar to the type was taken in 



