410 Prof. M'Intosh on the 



The most noteworthy bivalve mollusks are Pinna radisy 

 Isocardia cor, Solecwtus, Pandora incequivalvisy Siphono- 

 dentalium, and Cadulus. 



Amongst the univalves it is difficult to give forms specially 

 Zetlandic, though species of Odostomta, Trochus helicinuSj 

 T. groenlandicusy and Trichotropis horealis are very abundant 

 amongst the tangle-roots. The list includes Puncturella 

 noacldna, Aporrhais Macandrece, JefF., GolumheUa halia^eti, 

 Lyonsia, Lepeta, Trochus amabilis, the Jeffreysice, Pleurotoma 

 nivalis^ IScaphander librarius, Philine angalata, P. nitida^ and 

 Bossia papilUfera. A large number are common to the 

 Mediterranean. 



Of the Hemichordates perhaps the most characteristic is 

 Bliabdopleura Normanjii, Allman, which has not been found 

 in any other area in Britain. 



The Urochordates (Tunicates) are represented by an 

 occasional example of Pelonaia, a form only got in profusion 

 in our own neighbourhood, and by great numbers of ascidians, 

 chiefly of a common type. 



Salpa runcinata, Chamisso, again, is now and then met 

 with in the tow-nets, with Diphyes and Physophora^ as well 

 as a few Appendicularians. 



Amongst fishes one of the most characteristic is the torsk 

 [Brosmius hrosme), which is nowhere (in Britain) met with 

 in greater numbers or of larger size. Cod, haddock, and 

 green cod are of large size and abundant, and large pollack 

 are more common than in the south. Conger, again, are 

 especially numerous on the western shores. Ghimcera is not 

 uncommon. The large size of many of the forms — both 

 elasmobranch and teleostean — is in contrast with the eastern 

 and southern fish-fauna. 



Of mammals the most conspicuous are the finners and the 

 ca'ing whales {Globiocephalus melas), but small numbers of 

 rarer forms, such as Mesoplodon^ are occasionally met with. 

 Porpoises are often remarkably numerous, but seals are less 

 common than in the Outer Hebrides. 



In considering the relations of this our most northern area 

 with the arctic fauna, some remarks of Dr. Murray's in the 

 last volume of the 'Challenger' summary may here be 

 noticed. He says* : — " In polar waters a marked peculiarity 

 of the tow-net gatherings is the almost total absence of pelagic 

 larvEe belonging to benthonic organisms, and we know that 

 many of the Echinoderms and other shallow-water animals 

 of the Arctic and Antarctic regions are furnished with 

 pouches in which the young are reared ; the same appears to 

 be true of the animals living about and deeper than the mud- 

 * Summary of Eesiilts, vol. ii. p. 1459. 



