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



polliciforin process, and armed above it with a long straight spine. The dactylos is less 

 than half the length of the propodos, obtuse at the apex and carrying a long, slender, 

 hair-like spine. The other pereiopoda resemble the preceding, except that I could not 

 determine any evidence of a rudimentary chela, and that they appear to lose the spinous 

 character as they proceed posteriorly. The pleopoda, with the exception of the first, 

 which I have not been able to determine, are short and biramose. The posterior pair 

 which helps to form the rhipidura is remarkable, and, I believe, unique; the basal joint 

 is short and is furnished with a tooth on the anterior distal angle, and at the extremity 

 with two branches, one of which is very long, large, broad, and foliaceous ; it is narrow at 

 each extremity and wide in the middle, the distal end terminating truncately, and armed 

 at each angle with a small tooth or spine; smaller points or teeth fringe the margins 

 from the apex to the base, and at the base the lateral margins are curled over towards 

 the plate, thus giving strength to the basal portion of the appendage. The inner plate 

 is small, flat, rudimentary, and tipped with a few small hairs. 



Length, 25 mm. (l in.). 



Habitat. — Atlantic Ocean; surface (captured at night). 



Benthesicymus} Spence Bate. 



Benthesicyrnus, Sp. B., Ann. and Mag. Nat. Hist, ser. 5, vol. viii. p. 190, 1881. 



Body smooth. Tissue submembranous. Carapace anteriorly produced on the dorsal 

 surface to a short rostrum, laterally compressed and elevated to a crest. Cervical fossa 

 deeply marked ; a strong calcified ridge separates the lateral cardiac from the branchial 

 region. 



Posterior somites of the pleon laterally compressed and shorter than the rami of 

 the rhipidura. The telson is narrow, pointed, laterally compressed. 



Ophthalmopoda transversely compressed in their whole length, single-jointed ; 

 furnished on the inner side with an ocular tubercle. Ophthalmus not broader than 

 the peduncle. 



First pair of antennas has the first joint of the peduncle excavated to receive the 

 ophthalmopod, armed on the outer margin with a stout stylocerite, but without a 

 prosartema on the inner; the two succeeding joints are short, and the terminal one 

 supports two long flagella articulating at the extremity, the upper and outer being more 

 robust than the inner and lower. 



The second pair of antennas supports on the inner side of the first or coxal joint a 

 well-developed phymacerite ; the second joint carries a large, broad, and foliaceous 

 scaphocerite, strengthened on the outer margin by a rigid rib that terminates in a small 

 tooth or point ; the third joint supports on the inner distal side a small, kookdike, 



1 UiuSioUvpo:, an inhabitant of deep water. 



