Fishes of the Western North Atlantic 199 



Si-ze. The smallest specimens seen were 72.5 and 80 mm long, suggesting a 

 length (apart from the embryonic caudal filament) of about 70 mm at hatching. Some 

 males, and presumably females also, may mature at a length no greater than 450— 

 460 mm;* others, however, do not mature until they are somewhat larger, for the 

 claspers on a male 483 mm long are described as not fully formed." The greatest length 

 that we have found recorded for R.fyllae is 543 mm, but the maximum size attained 

 is probably somewhat greater. 



Developmental Stages. An egg capsule, probably of this species, taken in the Folden 

 Fjord on the west coast of Norway at 250—285 meters, was smooth-shelled and black, 

 40 mm long (exclusive of horns) by 24 mm broad, with the longer horns 32 mm and 

 the shorter pair 2 i mm long." 



Newly hatched specimens" differ chiefly from half-grown and adults in having less 

 thorny discs and the thorns along the midbelt of the back in a single regular row (p. 197). 



Habits. Of the habits of R.fyllae we know only: that the stomach of a small speci- 

 men contained small crustaceans (copepods, amphipods, mysids); that nearly all speci- 

 mens taken thus far have been from 148-983 fathoms (mostly 230-500 fath.), the 

 greatest depth recorded for it being 1,121 fathoms (2,050 m);^^ and that they came 

 from localities where the bottom temperature was between 3 and ^.^° C (37.4 and 

 41.9° F). 



Range. Barents Sea, Bear Island, western Spitzbergen, Murman Coast, northern 

 Norway, Denmark Strait west of Iceland, and Davis Strait off West Greenland; south 

 in the east to the southern part of the Norwegian Basin, inward along the Norwegian 

 trough to the Skagerrak between Norway and Denmark, Faroe Channel, the Atlantic 

 Ocean west and south of Iceland and the slope westward from the Straits of Gibraltar; 

 in the west to the southern slope of Georges Bank. The range of R.fyllae appears to 

 be defined by its preference for a narrow temperature range of a few degrees above 

 the freezing point of salt water (see above) and by restriction to at least moderately 

 deep water. 



Occurrence in the Western North Atlantic. Records of its capture in the western 

 Atlantic have been confined to four stations in the Greenland side of Davis Strait, 

 Lats. 63°3o' to 66°49' N and to one station on the southern slope of Georges Bank. 

 Since it appears to be confined in its northward dispersal to water of Atlantic influence, 

 there is no reason to expect it north of the Davis Strait Ridge. But a path would 

 appear to be open for it, so far as temperature is concerned, around the upper part of 

 the southern slope of the Ridge at depths of 400-600 fathoms. Watch should be 

 kept for it on the slope off Labrador and Newfoundland and southward at appro- 

 priate depths. 



8. See Clark (Rep. Fish. Bd. Scot. [1926], /, 1926: pi. 24, fig. a) for photograph of an adult male of this size as cal- 

 culated from its breadth. 



9. Jensen, Vidensk. Medd. naturh. Foren. Kbh., 1905: 234. 



10. Nordgaard, Tromso Mus. Skr., j {4), 1925: 9. 



11. See Clark (J. Mar. bid. Ass. U. K., 12, 1922: 624) for description and photographs of a very small specimen. 



12. For depth and temperature records for R.fyllae, see especially Hofsten (K. svenska VetenskAkad. Handl., 5.^ ['°]> 

 1919: 83) and Clark (Rep. Fish. Bd. Scot. [1926], i, 1926: 42). 



