20 CRUSTACEA MALACOSTRACA IV. 



and pseudorostrum is a little shorter than in my specimen, but I do not think that these differences are of 

 specific value. On the third maxillipeds he says: "I can see four teeth on the merus and, I think, three on the 

 carpus"; this statement is very important, as the number of teeth agrees completely with my description, 

 and both the joints mentioned have a higher number of such teeth than in any other species of Lexicon 

 described in the present paper, and are, besides, unusually robust. He observed 7 strong teeth on second 

 joint of first leg, but as I found 6 in an immature male the difference is of no importance; in my adult specimen 

 the first leg has a curiously week aspect, was perhaps not quite normal, and therefore the low number of 3 

 teeth on the lower side of second joint is not improbably a casual anomaly. Caiman's sketch of the uropods 

 shows the same difference as to length between exopod and endopod, furthermore that second joint of the 

 endopod is even slightly longer in proportion to first joint than in my tig. 6e; a difference as to spines on the 

 inner margin of first joint of the exopod is easily explained by the supposition that one spine or perhaps 

 two spines near the middle of the margin are lost in Norman's type. His specimen was secured rather near the 

 two places where my specimens were captured, and judging from the similarity in important characters 

 I think that my determination is correct. 



Occurrence. Taken by the "Ingolf" at two deep-sea stations in the warm area. 



Davis Strait: Stat. 24: Lat. 63°o6' N., Long. 56°oo' W., 1199 fath., temp. 2. 4 ; 1 ovig. female. 



Stat. 36: Lat. 6150' N., Long. 56 21' \V., 1435 fath., temp. 1.5 ; 2 immature males. 



The type, the only specimen hitherto recorded, was gathered by the "Valorous" at the entrance of 

 Davis Strait, Lat. 5g u io' N., Long. 50°25' W., 1750 fath. (Norman). 



16. Leucon robustus n. sp. 



(PI. I, figs. 7a— 7d). 



Female (with the marsupium half developed). Rather similar to L.sci-ratits, but showing some 

 sharp differences. Carapace about as deep in proportion to length as in L. serratus, but the anterior half of 

 the dorsal line is less convex; the serration on the dorsal edge is strongly developed, with the usual interrup- 

 tion considerably before the posterior end. The frontal lobe has a longitudinal row of 3 conspicuous teeth 

 a little above its lower margin. Pseudorostrum feebly upturned, moderately long, tapering to the acute end 

 (fig. 7 a), with the lower margin a little convex and a few teeth near the end (fig. 7 b). The antennal notch 

 is deep, angular at the bottom, with 2 or 3 minute teeth on its upper and 5 teeth on its lower margin; the 

 antero-lateral corner therefore considerably produced ; the lower margin of the carapace with about 9 teeth. 

 The free thoracic segments combined as long as carapace without pseudorostrum. Abdomen moderately 

 slender, as long as the whole cephalothorax. 



The antennulae (fig. 7b) are long; the peduncle is slender in proportion to length, reaching beyond 

 the end of pseudorostrum, with third joint somewhat shorter and considerably more slender than the second; 

 the three-jointed outer flagellum is slightly shorter than third peduncular joint; inner flagellum very short. 

 Third maxillipeds with a single spine on the proximal part of the lower side of second joint ; merus with one 

 well developed and another minute spine at the outer margin; carpus with 2 well-sized distal spines, one 

 below 7 and the other on the outer margin. First pair of legs (fig. 7c) robust; second joint with 3 strong teeth 



