CRUSTACEA MALACOSTRACA. III. 



227 



male mandibles is raised as a crest, which is irregularly dentate above; the two males measured 5-2 

 and 5-4 mm. in length, the mandibles not included. And the result of this detailed account is that I 

 can now safely refer G. cristata as a synonym to G. hirsuta. 



From the "Ingolf" I have two fine males belonging to G. hirsuta. Both specimens are 5 mm. 

 long, conspicuously narrower than G. robusta G. O. S., not quite three times as long as broad ; the sides 

 of the head (fig. 7 a) and thorax have numerous long, outstanding setse, and long setae are furthermore 

 found on the lateral, much protruding parts of fourth and fifth abdominal segments and on the uro- 

 pods (fig. 7 b). Last abdominal segment is distinguished by the shape of its major posterior part, which 

 is a much broader triangle than in G. robusta or G. abyssorum. — And some additional notes may be 

 made on these specimens. The eyes are somewhat small (fig. 7 a). The proximal half of the mandibles 

 above with a conspicuous crest irregularly adorned with several teeth. The head is anteriorly con- 

 spicuously produced at the middle, and the median anterior half of the surface evenly excavated; the 

 front margin is in one specimen (fig. 7 a) feebly concave, in the other distinctly longer with a low 

 triangular median protuberance. One specimen agrees with that figured by Sars in having the surface 

 of the posterior part of the third, and of the whole fourth and fifth leg-bearing segments smooth, 

 while in the other specimen these segments have numerous small but very distinct spikes. 



Occurrence. Taken by the "Ingolf at a single station. 



Davis Strait: Stat. 25: Lat. 63°3o' N., Long. 54°25' W., 582 fath., temp. 3-3°; 4 spec. (20" and 2 



young larvae). 



The specimen described as A. cristatus has been taken in Baffin Bay in Lat. ~]2°?p,' N., Long. 

 58°05' W., 116 fath. Finally recorded by G. O. Sars from a station somewhat south-west of Jan Mayen, 

 Lat. 70°4i' N., 263 fath., temp. -=- 0-3°. 



Distribution. Taken by the Norwegian North-Atl. Exp. west of Norway in Lat. 63° 10' N., 

 417 fath., temp. -f- ro°. 



161. Gnathia abyssorum G. O. Sars. 

 (PI. XVI, figs. 8 a— b). 



1897. Gnathia abyssorum G. O. Sars, Account, II, p. 56; PI. 23, fig. 2. 



1913. — schistifrons Stebbing, Trausact. Zool. Soc. London, Vol. XX, Pt. 4, p. 233 ; PI. XXIV B. 



Thanks to the authorities of the Christiania Museum I have examined the males investigated 

 by Sars, three specimens in all, but his description and figures were found to be misleading as to two 

 important features. Sars said nothing on the front median part of the head, but his figure shows only 

 a deepening of the broad front part of the upper surface, while the front margin is figured as being 

 a little convex with a small median tooth and a pair of minute submedian teeth. But his animals 

 differ as to these features strongly from his figure and agree with that drawn from one of my spec- 

 imens (fig. 8 a). It is seen that the surface is hollowed longitudinally in its anterior and somewhat 

 narrow median part, and the surface shows in front a rather broad and deep, at the base rounded, 

 incision, and the angle of the front margin at each side of the incision is produced in a rounded knot. 



My figure shows most of the incision dark, which is due to the fact that the lower wall of the head 



29* 



