Ad. s. Jensen: The Selachians of Greenland. 21 



The present author has been in the fortunate position of having at his disposal a 

 large number of specimens of Raja hyperborea of both sexes and at different ages, and 

 from an examination of this material he has come to the result, that R. hyperborea is a 

 distinct species from R. radiata. The characters by means of which they can most readily 

 be distinguished from one another are the following: 



Raja hyperborea Raja radiata 



The snout is somewhat prolonged, pointed The snout projects extremely little and in 



and projects distinctly in front of the outline is very obtuse-angled and al- 



anterior points of the breast fms. most rounded. 



The eyes are comparatively remote from The eyes are comparatively close together, 



each other, so that the interorbital so that the interorbital breadth at the 



breadth at the narrowest place is con- narrowest place is contained more than 



tained less than 3 times in the length 3 times in the length of the snout (to 



of the snout (to a line through the centre a line through the centre of the eyes). 

 of the eyes). 



22 — 31 spines in the mid line of the back 12 — 19 spines in the mid line of the back 



and tail^). and tail. 



The belly variegated, white with dark The belly uniform white^). 

 spots or dark^with white spots^). 



To this must be added, that the spines in R. hyperborea are on the whole narrower 

 than in R. radiata. Further, R. radiata has 2 scapular spines (probably constantly), 

 whilst R. hyperborea usually has 3 (sometimes however only 2). Lastly, the structure 

 of the teeth is quite different ; the teeth do not form a pavement, as is usual in the rays 

 and also in R. radiata (cf . fig. 4) ; from a relatively small base arises in R. hyperborea 

 a fairly long and narrow, needle-shaped point*), strongly inclined backwards (cf. fig. 5) ; 

 there is no recognizable difference between the two sexes. 



West Greenland. The occurrence of the species here was first noted in the year 

 1907, when the Governor of the colony Upernivik, H. Kraul, forwarded two rays, in 

 which to my surprise I recognized Raja hyperborea, which hitherto had only been known 

 from the deep water of the Norwegian Sea. Both were males, 490 and 650 mm long. 



M GiJNTHER States (1. c.) that in a specimen from the Færoe Channel he found only 16 dorsal 

 spines, but I imagine, either that some spines have been lost or that his specimen was Raja radiata. 

 — GoLLETT (1. C. 1905) notes only 20 spines in a specimen. My figures are based on ca. 40 specimens. 



^) In quite young specimens however the belly may be quite white, which is the case in two 

 of my specimens from the deep water of the Norwegian Sea, 176 and 191 mm long. 



^) Sometimes however dark spots have been observed on the otherwise white belly in R. radiata; 

 cf. Krøyer, Danmarks Fiske, IV, 1852—63, p. 942 and Pietschmann, Annalen des Naturhist. 

 Hofmuseum, 22. Bd., Nr. 4, 1907-08, p. 296. 



^) In 3 specimens I have found ^^ , *^ and cross-rows of teeth. 



