JAPANESE SHELLS AND PISHES. 101 



tte Mediterranean — Triton olearimn (properly olearius), Linne, 

 Saxicava arctica, L. (^8. rugosa, var.), and Lima sqiiainosa, La- 

 marck ; and eoniEQon to Japan and the Atlantic coast of Europe, 

 Triton olearium, Saxicava arctica, My a arenaria, L., and 3Iodiola 

 {Mytilus) modiolus, L. In his second volume lie noticed Lascea 

 ruhra, Montagu, which inhabits also the Mediterranean and the 

 Atlantic coast of Europe. We have thus five species in the same 

 category. Three of these species (viz. Mytilus modiolus, Lascea 

 rubra and Mya arenaria) are inhabitants of the shore and shallow 

 water ; Saxicava rugosa has a wide range of depth from low- water 

 mark to 1230 fathoms ; and Lima squamosa occurs in the coralline 

 zone. All the five species are Atlantic. I now propose to re- 

 cord from Capt. St. John's dredgings thirty-nine species as 

 common to Japan and the North Atlantic. These are exclusive 

 of Lima squamosa and Triton olearius, which have been already 

 noticed by Dr. Lischke ; and the number may be increased by 

 adding three species of Brachiopods {Terebratula vitrea, Gmelin, 

 var. minor, T. caput-serpentis, L., and Terehratella Spitzhergensis, 

 Davidson) mentioned by Mr. Davidson in the Proceedings of the 

 Zoological Society of London for 1871 ; three species of other 

 Mollusca (^Gemma gemma, Totteu, Coralliopliya litliopliagella. Lam., 

 and Piliscus commodus, Middendorif ) mentioned by Mr. Arthur 

 Adams in the Proceedings of the same Society for 1863 ; Limop- 

 sis ahyssicola, A. Adams, P. Z. S, 1869, Fossarus Japonicus, A. 

 Adams =i''. costatus, Brocchi. ; besides Limopsis aurita, two species 

 of Pecchiolia (P. acute-costata, Philippi, and P. granulata, Se- 

 guenza), Pyramidella nitidula,A. Adams, and other species which 

 were dredged by me in the Bay of Biscay during the ' Porcupine ' 

 expedition of 1870, as well as by Mr. A. Adams in the Japanese 

 seas. 



In giving the geograpliical distribution for the species now 

 about to be enumerated, I have added the range of depth for 

 such of them as I procured in the ' Porcupine ' Explorations of 

 1869 and 1870. This information will, I believe, be found useful. 



It will be observed that some of the species are littoral or in- 

 habit shallow water, while others inhabit the coralline and deep- 

 water zones. The modes of migration or transport from the 

 North Pacific to the North Atlantic, or vice versa, mvist conse- 

 quently be of different kinds. Some marine currents and tides 

 are superficial ; others are deep and sweep the bottom of the sea. 

 Now the latter kind of currents seem to be almost unknown. 



8* 



