JAMES A. GRIEG. 



[REP. OF THE "MICHAEL SARS" NORTH 



the Prince of Monaco with the "Hirondelle" and the 

 "Princesse Alice" has explored the waters round the Azores 

 and off the west coast of North Africa. The collections 

 of mollusca obtained by the French expeditions were 

 investigated by Locard 1 ), the collections of the Prince 

 of Monaco by Dautzenberg, partly alone, 2 ) partly in 

 collaboration with H. Fischer. 3 ) In this review no 

 reference has been made to the nudibranciate Gastropoda, 

 the species taken by the "Michael Sars" in the Atlantic 

 being either pelagic or belonging to moderate depths. 



It appears from the papers of Locard, Dautzenberg 

 and H. Fischer that several Mollusca occurring in the 

 great depths off the west coast of North Africa and around 

 the Canary Islands and the Azores are also met with in 

 deep water in the Bay of Biscay, e. g. 



Modiola polila Trophonopsis grimaldi 



Dentalium caudanl Buccinum atractodeum 



Keptunea abyssorum Pleurotomella bairdl, etc. 



The "Michael Sars" collection of Mollusca does not 

 contain a very great number of species, still it increases 

 the number of species common to both the northern and 

 southern part of the eastern North Atlantic. In the Bay 

 of Biscay (st. 10) were taken: — 



Pleurotomella thaumastopsis 

 Bathybela nudator 

 Surcula tenerrima 

 the two first named being previously known from the 

 Azores only, the third from the Azores and from the 

 Sargasso Sea. Off Ireland (st. 95) were taken Pleuroto- 

 mella bairdi, not previously known to the north of the 

 Bay of Biscay, and Clionella quadruplex, known from 

 the Azores and the west coast of Africa. Off the Hebrides 

 (st. 101) were taken Mytlllmeria flexuosa, known only 

 from this side of the Atlantic, from the west coast of North 

 Africa, and Dentalium caudanl, not previously recorded 

 to the north of Bay of Biscay. 



Comparing the results of the various expeditions 

 referred to it appears that many species are known only 

 from the northern part of the northeastern Atlantic, and 

 a still larger number only from the southern portion, where 

 most of the expeditions carried on their biological researches. 

 For instance the genus Marginella, which includes many 

 deep-sea forms, is not known from the northern part, 

 though it may be assumed with certainty that the number 



of widely distributed species will be increased as research 

 work goes on. Even now so many forms common to 

 both divisions of the northeastern Atlantic are known, 

 that as regards the mollusca, we may be justified in 

 regarding the deep water of the northeastern Atlantic as 

 one faunistic region, a rather natural assumption when seeing 

 that the hydrographical conditions are very uniform. There 

 is also a marked similarity between the western and 

 eastern sides of the North Atlantic, though not so close 

 as between the north and south divisions of the eastern 

 side, many of the species characteristic of the eastern 

 side being unknown on the American side. This is the 

 case with Troschelta berniciensis, a widely distributed form 

 in the eastern Atlantic. 



Very different from the North Atlantic molluscan 

 fauna is that of the cold area of the Norwegian Sea. 

 Illustrative in this respect is one of the stations of the 

 "Michael Sars", viz. st. 102, where the following species 

 were obtained: 



Neptunea curta Bela scalarls 



Neptunea mohni Philine flnmarchica 



Buccinum hydrophanum Cuthonella abyssicola. 



Of these the second and the lastnamed are charac- 

 teristic cold-water forms, known only from the depths of 

 the Norwegian Sea, while the other four species extend 

 more or less into the warmer areas encircling the deep 

 basin of that sea. Among mollusca also living in the 

 cold area of the Norwegian Sea may be mentioned: - 

 Pecten frigidus Neptunea danlelsenli 



Area frlelel Odostomia sublustris 



Natlca bathybii 



All these species are unknown from the depths of 

 the Atlantic, and the species characteristic of the latter 

 region are not met with in the Norwegian Sea, though 

 exceptions occur. The "Triton", for instance, took Tros- 

 chelta berniciensis in the cold area of the Faroe — Shet- 

 land Channel, 1 ) and the, "Armauer Hansen" Lyonsiella 

 abyssicola and Scaphander puncto-striatus in the cold 

 area off the Tampen Bank 2 ). Several southern warm-water 

 species were also taken in the cold area of the Norwegian 

 Sea by the Norwegian North Atlantic Expedition. 3 ) These 

 Atlantic mollusca, however, are also found on the banks 

 around the Norwegian Sea basin, and the cold water 

 stations where they were obtained are all situated so near 

 to the warm area that the hydrographical conditions vary 



J ) Locard: Mollusques testaeds et Brachiopodes, Resultats scientif. 

 Camp. "Caudan", Fasc. I, 1896. 

 Mollusques testaeds, Exp. Sc. du "Travailleur" et du 

 "Talisman", Tome 1, 1897, Tome 2, 1898. 



-) Dautzenberg: Contrib. Faune Malacol. des lies Acores. Res 

 Camp. Sc. par Albert I Monaco, Fasc. 1, 1889. 



■'-) Dautzenberg et H. Fischer: Mollusques prov. des draga- 

 ges effectues a I'ouest de TAfrique. Ibidem Fasc. 32, 1906. 



1 ) Jeffreys: Mollusca procured during the Cruise of H. M. S. 



Triton between the Hebrides and Faroes in 1882. 

 Proc. Zool. Soc. Loud. 1883, p. 389. 



2 ) Grieg: Evertebratfaunaen paa havdypet utenfor "Tampen", 



Bergens Museums Aa&bok 1914 — 15. no. 3. 



3 ) Friele & Grieg: Mollusca III, Noiw. N. All. Exp. 1876—78, 



Zool. part 28, 1901. 



