N0.1264. ILLUSTRATIONS OF AMERICAN SHELLS— BALL. 537 
we regard onl>" the .surface isotherms; and of the North Pacific and 
Bering Sea, including the adjacent portions of the Arctic and the 
northern islands of Japan. 
The species of the northeast Atlantic are as follows, omitting those 
of the Mediterranean and the Azores which are clearl}- su})tropical 
and do not enter the cold abysses or extend their range north of 
Gibraltar: 
BOREOTROPHON CLATHRATUS Linnaeus. 
This is the Marex clathratm Linnaeus, 1766, described from an Ice- 
landic specimen; it is the M. hamffius Donovan, 1803, and has been 
confounded with most of the t3^pical arctic species of BoreotropJion by 
authors. Morch stated in his catalogue of Greenland shells (1857) 
that this species was called Trltonium rossU by Leach, and he sent a 
specimen to the U. S. National Museum under the name of Trojjhm 
rlchardmn'ii Gray, from Spitsbergen. ' Both of these names appear to 
be unpublished — or at least I have been unable to find them in the 
literature. Reeve in his monograph of Fusus figures two species 
under the name of hanjjius (sic), but neither is the hamffini^ of Donovan. 
Morch also refers to the latter the fossil Mm'ex costatus of Hisinger, 
1837. It is a small but stout shell with very round whorls, a short 
and much recurved canal, ten to eighteen rather irregular, rarely 
prominent, more or less appressed laminar varices, no spiral threads, 
and only rarely any fine spiral striation. I hav^e seen none exceeding 
30 mm. in length, and at the shoulder the angle of the varices is 
rarely present; and if present, feeble and inconspicuous. Its range 
extends from Finmark to Greenland. I have never seen an American 
specimen. 
BOREOTROPHON TRUNCATUS Strom. 
This is Buednum truneatuui Strom, 1767; it is frequently con- 
founded with the preceding and with B. scalm'iformix Gould. It is a 
small species, not exceeding 17 mm. in length and usually smaller. 
It was figured liy Forbes and Han ley under the name of hamjfiius, but 
it is not the original hamjfius of Donovan. It has numerous low, 
rather irregular and close-set varices which are often obscurely crenu- 
late as if by obsolete spiral threads; there is rather strong spiral 
striation in well-developed specimens. The canal is short and obliquely 
truncate, the aperture and canal shorter than the spire. It is the most 
common North Atlantic species, and extends in 10 to 50 fathoms from 
Finmark to Greenland and south to Georges Banks on the American 
coast. 
BOREOTROPHON GUNNERI Loven. 
This species, discriminated ])y the accurate Loven in 1846, has been 
widely and generally confused with B. cfaf/mitif.s^ of which it is 
