A. E.. Verrili— Catalogue of Marine Mollusca. 477 
first it differs in being more elongated, but its coarser spiral sculp- 
ture, not becoming finer anteriorly, nor toward the shoulder, but dis- 
appearing on the subsutural band, gives a better diagnostic charac- 
ter; its ribs are also more sigmoid. From . Gouldii it differs in 
having the whorls much more sloping, and not squarely carinate- 
shouldered, nor nodulous; in not having straight ribs; in the spiral 
sculpture, and in having a shorter aperture and canal. In Bb. pleuro- 
tomaria the spiral sculpture is much less developed, and the spire is 
usually more slender. 
The positive identification of this shell with similar species 
described from Greenland and Northern Europe is not possible, at 
present. I have, myself, seen no specimens from those regions that 
could be called identical. Authors, both in this country and in 
Europe, have often mistaken other shells for this species, or have 
confounded several with it.* Ihave seen B. decussata, B. pleuroto- 
maria, B. exarata, B. Pingelii, and other species labeled as “ B, 
cancellata”’ in American collections. There is reason to believe that 
the confusion is eyen greater in foreign collections. 
Morch erroneously identified this species with B. Pingelii and D. 
cinerea Moller. Jeffreys, also, has identified this species with B. 
Pingel. 
Among the forms figured by Professor G, O. Sars, B. elegans 
Moller resembles closely some of the varieties of this species, and 
may be identical. Modller’s description of B. elegans is very brief 
and indefinite, but, so far as it goes, applies well enough to this 
shell. Jeffreys records a“ Pleurotoma elegans” trom the Gulf of St. 
Lawrence, which is possibly this species.  B. angulosa Sars also 
resembles the smaller and more slender varieties. 
The shell named LB. cancellata by Sars is a distinet species, to 
which I have elsewhere given the name, BL. Sursi/. (See p. 484.) 
It has a much coarser cancellation, produced by the more distant 
spiral lines, crossing very broad and nearly straight ribs. The shell 
itself is more narrow, and has flatter whorls. The uncini also differ. 

* The cut in Binney’s Gould (fig. 924), was probably made from some other species, 
but the figure is too bad for identification, The original figure by Dr. Mighels is 
very much better, 
