SMITH : ON ARCTIC AND ANTARCTIC MOLLUSCA. 163 
1. Gromus nitens, Jeffreys.—This species was originally described 
from specimens dredged in 1,750 fathoms at the entrance of Davis 
Straits, also off the west and south of Ireland in 557-1476 fathoms. 
It was obtained by the ‘‘ Challenger” in 1,900 fathoms off the Rio 
de la Plata. This identification was based on the examination and 
comparison of a single specimen from the latter locality. Although at 
the time considered to be the same as G. nitens, I do not now feel 
absolutely convinced of the identification. The comparison of a single 
example of such a minute form which is without any marked feature, is 
always unsatisfactory and inconclusive, and a recent re-examination of 
the shell in question seems to show that the concentric lines of growth 
are coarser than in typical examples. I should add that at the time 
when the Report on the ‘‘Challenger”’ Bivalves was written I had 
only a few poor representatives of the species for comparison. Since 
that time the British Museum has obtained a good series dredged by 
the ‘ Porcupine’ Expedition of 1869. I should further add that the 
genus is represented by a few very similar forms in the West Indian 
region, and also in deep water off Japan. 
2. Kextr1a suporpicutaris (Montagu).—A common British species 
recorded, on the evidence of two specimens, from Kerguelen Island. 
It is also known from Massachusetts (Gould), the Canary Islands, 
St. Helena (Smith), Port Elizabeth, Cape Colony (Sowerby), Mazatlan 
(Carpenter). Another species (XH. rotunda, Deshayes), doubtfully 
separable from the present form, has been quoted from Queensland 
(Deshayes), New South Wales (Angas), Bass Straits (Smith), Cape 
Colony (Sowerby). Although it might be hazardous without a knowledge 
of the soft parts to declare that the two forms mentioned are certainly 
conspecific, I must say on the evidence of the shells alone I fail 
to perceive where the line of demarcation occurs. I imagine that 
difference in locality was the chief reason which induced Deshayes to 
separate his so-called species from the well-known European form. 
Like the foregoing Glomus nitens, the present species offers no 
specially distinctive conchological characters which will separate it, 
beyond doubt, from other allied forms. The genus is cosmopolitan. 
3. Myrinus epuuis, Linn.—Since Sir John Murray quoted this 
well-known mollusc in his list of species from the extra-tropical 
regions of the northern and southern hemispheres, it has been cited 
from Cape Colony (Sowerby), Rio Grande do Sul and St. Catharina on 
the east coast of South America (Von Jhering). The South African 
locality may be erroneous, for the I. meridionalis of Krauss, said by 
Sowerby to be a variety of edulis, is monomyarian, and quite distinct 
from the common European shell, which is dimyarian. JZ. edulis has 
been quoted from New Zealand (Hutton, Smith, etc.), Great Barrier 
Island, Auckland Islands, Campbell Island (Hutton), Kerguelen Island 
(Smith). Also from California as I. trossulus, Gould, considered by 
Jeffreys and Dr. von Jhering synonymous with I. edulis. 
From the foregoing remarks it is seen that this species has such an 
extensive distribution that its occurrence in Arctic and Antarctic 
seas is in no way surprising. The members of this genus also are 
