34 



Mindeskrift for J. Steenstrup. XXX. 



ribs are densely beset with small stiff rods serrated at the tip and ca. 2 mm in length, 

 so that the capsule has a velvety appearance (fig. 11). Lutken put forward the sug- 

 gestion, that they perhaps belonged to Raja fyllae (Vidensk. Meddel. Naturhist. Foren. 

 1887, p. 4), but this has later proved to be a small species. For my part I am inclined 

 to believe, that these large egg-capsules belong to Raja spinicauda discovered by the 

 "Tjalfe" Expedition, which is indeed a species of considerable dimensions and which 

 occurs just in the district (Julianehaab), from which the missionary Jørgensen for- 

 warded the capsules. 



On the other hånd, it is not only the egg-capsules of the present species, but also 

 the comparatively common capsules of Raja radiata, which have given rise to the Green- 

 landers' "Kollwsiuternak" and the Zeus Gallus of Fabricius. In a letter of 30th Sep- 

 tember 1841 the above-mentioned missionary Jørgensen writes to J. Reinhardt: "I 

 have convinced myself, that the Greenlanders at Frederikshaab also call a ray egg "Kol- 

 Iwsiuternali" and have no doubt therefore, that Fabricius has been misled by their 

 description to record Zeus Gallus as a fish of Greenland". But at Frederikshaab, so 

 far as I know, no other ray occurs but Raja radiata. 



The distribution of some Greenlandic Selachians elucidated by 

 the hydrographical conditions. 



It is well-known, that the broad arms of the sea which extend up between 

 Greenland — Iceland— the Faeroes— Shetlands and which connect the Norwegian Sea 

 with the Northern Atlantic, are cut across at a certain depth by submarine ridges. 

 Thus, almost in the middle of the Denmark Strait between Greenland and Iceland (at 

 66° N. L.) there is a submarine ridge, which at its shallowest part lies quite 300 fm. 

 under the surface. Between East Iceland and the Faeroes there rises a broad ridge 

 in a depth of about 250 fm. ; its shallowest part, N. W. of the Faeroes, lies not more 

 than ca. 275 fm. below the surface. From the Faeroes this ridge is continued as the 

 narrow, so-called Wyville-Thomson ridge, with a maximum depth of 330 fm., towards 

 the Hebrides and is connected with the large plateau which forms the bottom of the 

 North Sea. 



The depths of the ocean north of these ridges are thus completely separated from 

 the depths of the Atlantic and it is only in the uppermost 300 fm. that there can 

 be an exchange of water-masses between them. The ridges thus constitute the divid- 

 ing line between two kinds of bottom-water: north of the ridges below ca. 300 fm. 

 there is always cold water characterised by low temperatures, below 0° C. (down to 



