1124 



SCANDIXAVIAX FISHES. 



merits of these parts, tlie variations in this respect are 

 equally great in the two species and overhi]:> each other. 

 Tlie spiny armature of the skin is generally weaker 

 and on the dorsal side sparser than in the common Skate 

 — sometimes it is entirely wanting — but on the ventral 

 side it is more uniform and more extensive, except at 

 the outer margins of the ventral fins and on the tail, 

 which in some instances, however, has a strip of fine 

 spinulu' along the middle of its under surface. The aculei 

 of the young are persistent, at least in the males, on 



In a male 14'* ^ dm. long tlie length of the head 

 to tlie occiput measured 27"8 %, that of the snout from 

 the anterior margin of the eyes 21 %, and the distance 

 between tlie mouth and the tip of the snout 22'3 %, of 

 the length of the liody. The last-mentioned distance 

 was 68 % of that between the moutli and tlie cloacal 

 aperture, a percentage which, according to Collett's 

 figure, amounts in a female 19 dm. long only to 56. 

 The breadth of the mouth -was 40 % and the internasal 

 width 4.3'8 % of the length of the snout". The iaw- 



Mii*" 



Fig. 324. Black-bellied Skate {Raja nidrosiensis), cT, from Troudhjem Fjord, March 17, 1891. ConserTator Stokm. '/,„ nat. size. 



The skeleton of this specimen is figured above, p. 1004. 



the orbital margins, and are also retained in both se.xes , teeth are similar to those of the common Skate both 



on the upper median line of the tail, a few usually re- 

 maining as well between the two dorsal fins; but ac- 

 cording to CoLLETT only the females are furnished with 

 a row of aculei on each lateral margin of the tail. 



in number and form''. 



The coloration of the dorsal side, according to CoL- 

 LETT, is of a dark grayish bi'own, and the ventral side 

 is nearly brownish black, ))lackest in the middle'. The 



imoiinls in a female 19 dm. long hardly to 37; and the moutli seema 



" According to Collett's figure the last-mentioned percentage 

 to have been even narrower than that of the specimen described above. 



' The distinction adduced by Moreau between the dentitions of Raja tiuicrorfiijncJuis and R. batis evidently depends on differences 

 of age and sex. 



' According to Carus Raja macrorhynchus is also dark brown (fiisca) both above and underneath. 



