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



line between it and the carapace projaer is well defined and continued back to the posterior 

 limit of the latter. The thoracic sternum is broad between the chelipedes and becomes 

 narrow between the second pair of legs ; both in front of and behind the chelipedes it 

 spreads out to form paired lateral pointed processes. 



The chelipedes are slightly granular, the merus and ischium unarmed ; the carpus 

 possesses a single small spine overhanging the insertion of the following joint ; the 

 propodus is triangular, the immobile finger forms a straight line with the lower border of 

 this joint (which has a raised margin), its inner border is irregularly dentate, one tooth 

 in particular being of large size ; the dactylus is entire. The ambulatory limbs are 

 sparingly ciliated and smooth, with the exception of the last pair, which are faintly 

 granular ; the dactyli are hatchet-shaped ; the last pair of legs are of moderate length and 

 slender, with the carpus serrated on its anterior margin. 



The second and third abdominal segments are both slightly wider than the first ; the 

 apex of the telson is acute. 



The single specimen taken is apparently a young male, and gives the following 

 measurements: — Breadth of carapace 87 mm., of fronto-orbital border 6 '2 mm., length 

 of carapace 11 7 mm., of chelipede 9 mm., of last leg 7 mm., of external maxillipede 

 5 "5 mm. 



In Notopus dorsipes (Fabr.) De Haan, the dorsal carina is more marked, and a row 

 of strongly developed tubercles (almost spiniform) cross this at right angles near the 

 anterior end of the carapace ; the spines on the antero-lateral border are placed close 

 together, and the last two are not separated by a wide interval as in Notopus ovalis. 

 Notopus atlanticus, Studer, has the antero-lateral border armed with four spines (only 

 three are present in Notopus ovalis), and the rostrum is much narrower than in the 

 Challenger species. 



Habitat. — Station 192, oflF Little Ki Island ; depth, 140 fathoms ; bottom, blue mud. 

 Taken along with the last species. 



Genus Cosmonotus, Adams and White. 



Cosmonotus, Adams and White, Proc. Zool. Soc. Lond., p. 227, 1847; Voyage of H.M.S. 

 "Samarang," Crust., p. GO, 1848. 

 „ Dana, U.S. Explor. Exped., vol. xiii.. Crust., part i. p. 404, 1852. 



Carapace ovate, smooth, compressed laterall)^, with a prominent median keel strongly 

 marked in front but fainter posteriorly. Fronto-orbital border narrow, concave, without 

 a central rostrum ; lateral borders of the carapace convex, unispinose. In other respects 

 agreeing with Notopus. 



Only a single species is known. 



