ON DREDGING AMONG THE SHETLAND ISLES. 431 



Fourth Report on Dredging among the Shetland Isles. 

 By J. GwYN Jeffreys^ F.R.S. 



Ik spite of the weather, whicli was worse than usual in this stormy region, 

 some additional results of no slight interest were obtained. The three requi- 

 sites of such enterprises (time, money, and experience) were not wanting ; and 

 the valuable cooperation of Mr. Norman, Mr. Waller, and Mr. Dodd, aided by 

 a good yacht and crew, and by a large stock of apparatus, left nothing to desire 

 except calmer seas. Dr. Edmondston and his family again did aU in their 

 power to promote our endeavours ; and Mr. Cheyne, of Edinburgh, kindly 

 placed his house at Tanwiek at our disposal. 



Discoveries in natui'al histoiy are of several kinds, aU of which are nearly 

 equally important : — 1. New species or forms. 2. Geographical distribution. 

 3. Habits of animals, including in the present case those supposed to be depen- 

 dent on the depth of water. 4. Geological relations. 5. Extraneous inci- 

 dents. 



AU these I will now notice as regards the MoUusca. Other branches of the 

 marine Invertebrata wUl be treated of by Mr. Norman, Mr. Waller, and Dr. 

 M'Intosh ; and Dr. Giinther has kindly promised to report on a few small 

 fishes caught in the dredge. 



1. Neiv Species. — The species I am about to enumerate are new to the 

 British fauna, but not to science. 



TerebrateTla Spitzhergensis, Davidson. 



A fresh and perfect, although dead specimen occui'red in 80-90 fathoms off 

 Unst. The only locality hitherto recorded for this shell in a living state 

 is Spitzbergen. It was found by Hisinger and myself in a fossil state at 

 Uddevalla, and last year by Messrs. Crosskey and Eobertson in another raised 

 sea-bed near Christiania. There is, of course, a possibUity that the Shetland 

 specimen also may be fossil ; but it has all the appearance of being recent ; 

 and Terehratula cranium and T. caput-serpentis (both of which are likewise 

 arctic species) hve in the same place where this specimen of Terebratella 

 Sjntzbergensis was dredged. 



MhgncJionella psittacea, Gmelin. 



A specimen (unfortunately broken in dredging) was found with Terebratella 

 Spitzbergensis, Terebratida cranium, and T. caput-serpentis. This was filled 

 with soft mud, in which was a fresh, but dead young specimen of R. psittacea. 

 I had on a former occasion dredged a full-grown specimen and a young one 

 (both quite perfect, although not living) off IJnst. In ' British Conchology,' 

 vol. ii. pp. 22 and 23, is an account of all the specimens said to have been 

 taken by Capt. Laskey and others in the British seas ; and I am stiU convinced 

 that most of these reported discoveries were mistakes, and that some of the 

 specimens are fossil. The present case is free from doubt, except on the latter 

 ground. Single valves of Pecten Islamlicus, Tellina calcaria, and Mga trun- 

 cata, var. Uddevallensis, are not uncommon on the northern and eastern coasts 

 of Shetland, and were procured with T. Spitzbergensis and It. psittacea ; but 

 the former had an uumistakeably fossilized or chalky aspect, and never were 

 perfect or had the valves imited. It seems to be an established rule that in 

 all species of marine invertebrate animals, which are distributed through the 

 European seas, northern specimens excel in size those from the south ; and 

 thus the comparative size of living and dead specimens of arctic species found 

 in the Shetland seas may serve as an additional test to distinguish which of 



