28 AMERICAN JOURNAL 



conditions, is stated by Mr. Watson* to be about 800 feet higber 

 than the marine deposit. The height of the hiyer of sea-shells 

 on Moel Tryfaen in Carnarvonshire (evidently the remains of an 

 ancient beach) exceeds that of the similar deposit at Cardigan 

 by more than 1300 feet ; and the difference of height observed 

 in the case of other fossiliferous deposits in the north of England 

 {e. g. Manchester and Kelsey Hill) shows that the disturbing 

 movement has been unequal, and probably not synchronous, over 

 the same area. It would seem that the extent of such oscillation 

 has not altogether amounted to 2000 feet in the British Isles, 

 taking Moel Tryfaen as the greatest height, and the Shetland 

 sea-bed as the greatest depth at which quaternary shells of re- 

 cent species occur. The Scotch and Irish deposits, however, are 

 on the whole far more ancient than those of Wales and England, 

 judging from their geographical nature; the former are chiefly 

 arctic, and the latter merely northern. Whether other parts of 

 the North Atlantic sea-bed have undergone a much greater change 

 of level since the tertiary epoch is not so well established. Dr. 

 G. C. Wallich, in his admirable and philosophical treatise, f with 

 which all marine zoologists and geologists are, or ought to be, 

 familiar, believed that certain starfishes which he had procured 

 at a depth of 12G0 fathoms (7560 feet) in lat. 59° 27' N., long. 

 26° 41' W., about halfway between Cape Farewell and the north- 

 west coast of Ireland, were originally a shalloAV-water species, 

 but had gradually, and through a long course of generations, 

 accommodated themselves to the abnormal conditions incident on 

 the subsidence of the sea-bed. | The starfishes in question, which 

 he refers to the Opldocoma granulata of Forbes [Asterias nigra 

 of 0. F. Miiller), appear, however, to belong to a different spe- 

 cies, which inhabits deep water. In an important paper by Pro- 

 fessor Sars, on the distribution of animal life in the deptiis of 

 the sea,§ he states that Ophiocoma nigra ((9. granulata, Forbes) 

 is certainly found in shallow water, viz., from 2 to 30 fathoms, 

 on the coast of Norway, but never at a greater depth so far as 

 is yet known, and that it does not range north of the firth of 

 Drontheim. He is of opinion that Dr. Wallich's species is Ophia- 

 cantlia spinulosa of Miiller and Troschel, a well-known and Groen- 

 landic species, which is not littoral, but rather a deep-water kind, 

 viz., from 20 to 190 fathoms ; and he infers from Wallich's own 

 account that the last-named species, instead of Ophiocoma nigra 

 ov granulata, was the one taken by the 'Bulldog' sounding in- 



*Loc. cit. p. 524. 



t The North Atlantic Sea-bed, 1862. 

 XLoc. cit. p. 41. 



IVid.-Sesk. Forhandl. 1864: Hr. Sars, '' Bemaerkninger over det 

 djriske Livs Udbredning i Havets Dybder." 



