
A. E. Verrill— Catalogue of Marine Mollusca. 575 
fathoms; off Cape Cod, 94 to 122 fathoms; on George’s and Le 
- Have Banks; and off Halifax, Nova Scotia, at various depths, from 
70 to 430 fathoms. 
It is very common south of Martha’s Vineyard, in 200 to 506 
fathoms, and is less frequently dredged in 76 to 150 fathoms, those 
from the shallower stations being mostly dead, or young. It oc- 
eurred at 32 stations in this region. It was particularly abundant 
at 894, in 365 fathoms; 938, in 310 fathoms; 939, in 258 fathoms; 
997, in 335 fathoms. 
Gulf of St. Lawrence! (coll. Whiteaves). Gulf of Mexico, “Blake” 
Exp. Greenland; Spitzbergen. Lofoten I. to the Mediterranean; 
20 to 1170 fathoms. 
Fossil in the Pliocene and Post-pliocene of Europe, in Norway, 
Italy, and France. ae , 
Variety Firielei was taken by the Valorous and Norwegian Arctic 
Expeditions, in 459 to 1333 fathoms. Forms apparently identical 
with the latter, occurred, with the other varieties, off Martha’s Vine- 
yard, in 192 to 487 fathoms, stations 869, 892, 895, 1880; 949, in 100 
fathoms, 1881. 
Arca pectunculoides, var. crenulata Verrill, nov. 
Shell with a regularly crenulated inner margin, small, short, in- 
flated, somewhat oblique, having nearly the outline of variety Frielez, 
defined above, but somewhat more tumid. The posterior end is 
regularly and circularly rounded ; the ventral margin is broadly and 
somewhat obliquely rounded, the curvature being continuous to the 
dorsal angle; the dorsal edge is straight, with a distinct angle at 
each end, but both ends curve outward beyond the angles. Umbos 
swollen; beaks acute, curved inward and forward, not coming very 
near together, but leaving a deep and rather broad, well-defined liga- 
mental and lunylar area between and in front of them. Hinge- 
margin thin, straight, in the larger specimens with about 9 or 10 
posterior, and 6 or 7 anterior teeth, which are well-defined, small, 
regular, not very oblique, and not laminar. Smaller examples have 
about 4 or 5 anterior and 6 or 7 posterior teeth. The hinge-margin 
is a little wider anteriorly, where denticulated, and the anterior 
teeth are somewhat larger than the posterior ones, and a little more 
oblique. The middle of the hinge-margin is edentulous and narrow, 
for a short distance, below the beaks. The posterior series of teeth 
is longer, and extends nearly to the beaks. The crenulations of the 
