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



1. Paranebalia longipes, Willemoes Suhm (Pis. I., II.). 



Nehalia longipes, Willemoes Siilim, On some Atlantic Crustacea from the Challenger Expedition, 



iii; Trans. Linn. Soc. Lond., ser. 2, vol. i. p. 26, pi. vi. 1879. 

 Paranehalia longipes, Claus, Grundziige der Zoologie, ed. 4, p. 576. 



Specific Characters.— Cava])ace as seen laterally, oval in form, covering besides the 

 trunk also more or less completely the sides of the pleon ; rostral plate oblong, narrowed 

 in front and terminating in a spiniform projection. Posterior abdominal division or 

 tail scarcely longer than pleon and suddenly much narrower, the two middle segments 

 denticulate at the posterior edge. Eyes slightly curved and tapering to the end, upper 

 side strongly denticulate. Antennulse with the terminal expansion of the peduncle 

 broadly lanceolate and armed with about twelve serrations along the outer edge ; 

 flagellum not attaining half the length of the peduncle, and composed of but five 

 articulations, the first by far the longest. Antennae with last joint of peduncle longer 

 than the preceding and armed at the anterior edge with two recurved denticles, flageUum 

 shorter than peduncle and six-articulate. Epipodite of last pair of branchial legs 

 produced above to a slender flap. The three posterior pairs of pleopoda with the basal 

 part strongly serrate at outer edge. The two pairs of rudimentary caudal limbs neai"ly 

 equal in size. Caudal rami about as long as the three last caudal segments combined, 

 outer edge minutely spinulose, inner setose, apex blunt, tipped with a fascicle of exceed- 

 ingly long and slender setae. Length of adult female 6 mm. 



Remarks. — In the above diagnosis I have given some characteristics, to which I am 

 inclined to believe should only be attributed the value of specific marks. As, however, 

 the above named species is the only representative of the genus as yet known, a strictly 

 specific diagnosis cannot of course be drawn up at present. 



Description. — Among the material sent me for examination no male was found, all 

 the specimens being either immature or adult females, partly laden with eggs or embryos. 

 But the late Dr. v. Willemoes Suhm has shortly described and figured the adult male of 

 this form, wliich exliibits some very interesting features not found in the male of Nehalia. 

 Unfortunately the male specimens examined by that naturalist have been lost, and thus 

 my investigations have been solely restricted to the female sex. The length of the 

 adult female docs not exceed 6 mm. and hence the present form is rather inferior in size 

 to the known species of Nehalia. 



All the specimens having been preserved in strong spirit, the body has become 

 rather opaque and of a dark brownish colour, showing however in most of them, at the 

 anterior part dorsally, a pecuHar marking in the form of two symmetrical, slightly 

 ramified patches of a whitish colour (see PL II. fig. 1). Whether this marking is due to 

 a merely external colouring or indicates some underlying internal tissue, I have not 

 been able to ascertain. By carefully preparing a specimen with absolute alcohol and 



