606 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.41. 



REMARKS ON GEOGRAPHICAL DISTRIBUTION. 



It is necessary once more to insist on the fact that our knowledge 

 of the Cumacea, except in one or two narrow areas, is far too frag- 

 mentary to admit of any profitable discussion of the subject of 

 geographical distribution. Even the rich collections from the New 

 England and Alaskan coasts now examined present, in all proba- 

 bility, only an incomplete and one-sided picture of the Cumacean 

 fauna of these regions. The employment of other methods of col- 

 lecting, specially adapted for obtaining the more minute organisms 

 of the sea bottom, would no doubt add very largely to the lists of 

 species and materially alter the aspect of the fauna as compared 

 with that of better known regions. Nevertheless, while no impor- 

 tance can be attached to the negative features of the lists here given, 

 there are one or two positive features which seem to be of sufficient 

 interest and importance to merit further consideration. These are 

 concerned with the relations between (1) the North Pacific fauna 

 and those of the Arctic and Atlantic Oceans, and (2) the relations 

 between the faunas of the eastern and western coasts of the Atlantic. 

 As regards the first point, the following species ^ are recorded 

 below from both the Pacific and Atlantic coasts: 



Leucon nasica. 



Eudorellopsis Integra. 



Diastylis ratlikii. 



Of these, D. ratlikii is known to have practically a circumpolar range 

 in Arctic seas, the only considerable gap being in the unexplored 

 waters of the Arctic-American archipelago, between Wellington 

 Cliannel and Point Franklin, Alaska. Leucon nasica maj^ also be 

 found to have a circumpolar distribution, since it is already known 

 from west Greenland eastward to the mouth of the Yenisei. The 

 remaining species, Eudorellopsis integra, is especially interesting since 

 it is known only from Bering Sea, west Greenland, and the northern 

 part of the Atlantic coast of America. It is very undesirable to press 

 too far the evidence from a single case of this kind, more especiaUy 

 when it concerns a minute bottom-living species, whose apparent 

 absence in many localities may be due to imperfect collecting, but it 

 is at all events suggestive that a similarly limited range is recorded 

 for several species of decapod Crustacea. The crab Chionoecetes opilio 

 and the shrimps Nectocrangon lar and Spirontocaris grcenlandica may 

 be mentioned as examples.^ These and other similar instances seem 



' Excluding, for the present, Campylaspis horrida and Lampropsfuscata, the identification of which in the 

 Pacific is doubtful. 



2 Ortmann, Bronn's Thierreieh, Crustacea, Abth. 2, 1900, p. 1265. See also Rathbun, Harriman Alaska 

 Exped.,vol. 10, 190t, pp. 61, 137, and 174; and Hansen, Danish Ingolf-Exped., vol. 3, Crust. Malacostraca, I, 

 1908, pp. 12, 69, and 64. 



