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



Habitat.— Station 188, September 10, 1874, Arafura Sea; lat. 9° 59' S., long. 139° 42' E.; 

 flepth, 28 fathoms; bottom, green mud. A single male specimen. 



Remarks. — Notwithstanding the fact that it has five teeth instead of six on the 

 dactylus of the raptorial claw, and the very slight development of the longitudinal carinse 

 on the hind body, this species bears such a very close general resemblance to the well 

 known Squilla nepa, that I was at first inclined to regard it as a smooth specimen of this 

 species, with an accidental variation in the number of teeth on the dactylus, and the more 

 especially as Squilla nepa is known to occur in the region where the specimen was 

 obtained. More careful examination, however, reveals so many minute points of difference 

 in all parts of the body that I think there can be no doubt of its distinctness. The 

 following, which are the most conspicuous differences, will serve to distinguish it with 

 readiness from the latter species. Squilla nepa has six and Sqtiilla quinquedentata five 

 spines, including the terminal one, on the dactylus of the raptorial claw. The carinse on 

 the anterior edge of the third joint or carpus of the raptorial claw of Squilla nepa is 

 irregularly dentated, while it is entire and smooth in Squilla quinquedentata. The 

 rostrum of Squilla nepa narrows slightly towards the tip, while that of Squilla quinque- 

 dentata is more nearly rectangular. The longitudinal cardiac sutures on the posterior 

 portion of the carapace are divergent posteriorly in Squilla nepa, and convergent in 

 Squilla quinquedentata. The submedian carinse of the fifth abdominal somite are 

 parallel in Squilla nepa, and divergent posteriorly in Squilla quinquedentata. 



Squilla lep>tosquilla, n. sp. (PI. I. figs. 1, 2). 



Diagnosis. — Ocular segment in front of rostrum. Eyes broad and sub-tri- 

 angular. Exposed segments of hind body with submedian carinae. Dactylus of raptorial 

 claw with four spines, including the terminal one. Antennulary somite ver}^ long, 

 reaching to tip of rostrum on middle line, and with its antero-lateral angles prolonged 

 forwards into acute spines. First thoracic somite jjartially exposed dorsally. Lateral 

 margins of second, third, and fourth thoracic somites acute. Telson with a long slender 

 median spine on dorsal surface, and three pairs of marginal spines, of which the second or 

 intermediate pair are much the longest, and the external pair shorter than the submedians, 

 and blunt, while the others are acute. First antennae very long. 



General Description. — Rostrum nearly twice as long as wide, subtriangular, with a 

 rounded anterior end. Width of carapace between antero-lateral angles about ^^ of its 

 greatest width, which is equal to about two-thirds (^^) of its length. The length of the 

 carapace is -j^oSjIj of the total length of the body, and its antero-lateral angles are produced 

 foru^ards as long acute spines, while the postero-lateral angles are prominent and broadly 

 rounded. The gastric area of the carapace is convex and elevated, -nath an obscure 



