Cumacea of the Canadian Arctic Expedition 1913-1918. l 



By W. T. CALMAN, D. Sc. 



Department of Zoology, British Museum (Natural History). 



The collection of these Crustacea obtained by Mr. F. Johansen during the 

 Canadian Arctic Expedition although small is of considerable interest as coming 

 from a region hitherto quite unexplored in respect of this as of most other groups 

 of marine animals. 



The full synonymy of the species mentioned will be found in Stebbing's 

 revision of the Cumacea (Das Tierreich, Lief. 39, 1913). Some important 

 records of distribution have since been published by Hansen (Danish Ingolf- 

 Expedition, Vol. Ill, 6 (Malacostraca IV.) 1920. Most of the American records 

 are quoted in my paper on the Cumacea of the U. S. National Museum (Proc. 

 U. S. Nat. Mus., XLI, 1912, p. 603). 



Diastylis rathkii Kr^yer. 



Locality "Station 48a, Goulbourn point, Bathurst inlet, Northwest 

 Territories, about lat. 67 35' N., long. 108 40' W., May, 1916. From stomach 

 of Coitus quadricornis." 1 female. 



Remarks. The partially digested specimen is not in a condition to permit 

 accurate determination of specific characters, but from its size (19 mm.) and 

 from the absence of a marked gap between the 2nd and 3rd legs it may be referred 

 to this widely distributed species rather than to D. sulcata. 



To the synonymy of this species should, I think, be added Alauna uncinata 

 Baird (in Sutherland's "Journ. Voy. Baffin's Bay", 1852, Vol. II, Appendix, p. 

 cciv, text-fig. 2). The specimen, which was from Assistance bay, Cornwallis 

 island, Barrow strait (about lat. 75 N., long. 95 W.) is not to be found in the 

 British Museum collection, but from the figure, it almost certainly belonged 

 to D. rathkii. 



Diastylis sulcata Caiman. 



Locality. Station 27s. "Collinson point, Alaska, lat. 69 59' 06" N., long. 

 144 49' 57" w., 3rd October, 1913. About 3 fathoms. Mud with algae." 

 Many specimens. 



Remarks. The females, none of which is ovigerous, agree very closely 

 with the specimens which I described (Proc. U.S. Nat. Mus. XLI, 1912, p. 654) 

 from an Alaskan locality far to the south-west of that now recorded. The 

 adult males, all of which are badly damaged, differ from typical males of D. 

 rathkii in the rather more elongated carapace. The ridge crossing the dorsal 

 surface behind the ocular lobe is less marked than in the female and bears no 

 teeth, but the vertical continuation of it on the side of the carapace is strong 

 and serrated and is continued, below the lateral keel of the carapace, as the upper 

 lip of a deep supra-marginal furrow. 



In neither sex have I been able to perceive pigment or any distinct evidence 

 of ocular structure on the small ocular lobe. In preserved specimens of D. 

 rathkii, however, the eye is no more distinct than it is here, and the use made 

 of this character by Stebbing (Das Tierreich, Cumacea, p. 90) for separating the 

 two species is not justified. 



Diastylis sulcata var. 



Localities. Station 28o. "Collinson Point, Alaska, 8th July 1914. From 

 stomach of Salvelinus malma. }} Many females (some ovigerous) and young- 

 males. 



1 Published by permission of the Trustees of the British Museum. 



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