500 
A. E. Merrill- — Catalogue of Marine Mollusca. 
the hinge-plate, there is a more or less marked rib, running outward 
and backward, at the base of the rostrum. - The rostrum is somewhat 
variable in form and sculpture; it is usually slightly turned up at 
the end ; commonly it is more or less covered with small, unequal, 
radiating ribs, stronger on the ventral half, and distinctly lamellose 
on the dorsal side, toward the end; sometimes the ribs are obsolete 
on the basal portion. 
Variety, Clirta Jeffreys. 
Xecera curta Jeffreys, Ann. and Mag. Nat. Hist., Dec., 1876, p. 495 (name, not de- 
scribed) ; Proc. Zool. Soc. London for Nov., 1881, p. 943, pi. 71, fig.JO, Apr., 
1882. 
Some specimens, from station 871 , in 115 fathoms, agree so well 
with the form recently described and figured by Mr. Jeffreys, that I 
do not hesitate to consider the latter a variety of this species. Our 
specimens of this variety differ from the typical form in having a 
shorter and more upturned rostrum ; in the radiating ribs on the an- 
terior half becoming much finer, and sometimes almost obsolete; and 
in the somewhat shorter and rounder form of the shell, it being more 
abbreviated anteriorly. 
Mr. Dali identifies our typical shells, which I sent him for compar- 
ison, with the species recorded by him, as probably M. alternata 
D’Orb. To me, D’Orbigny’s shell appears to be a distinct, though 
allied, species. 
Jeffreys, in the paper last quoted, suggests that our shell is iden- 
tical with his N. striata, but the latter has numerous, nearly equal, 
small, radiating ribs, not becoming decidedly stronger and wider 
apart posteriorly, as they do in our shell, and as they were described 
in our original description. Perhaps all these forms may eventually 
prove to be varieties of one species. 
In 1880 , this was dredged at about 90 to 100 miles south of New- 
port, R. I., and Martha’s Vineyard, in 85 to 120 fathoms, stations 
871 , 873 , 874 , 876 . Several living specimens of various sizes. In 
1881 it was taken at stations 949 , 1035 , 1038 , 1040 , in 93 to 146 
fathoms. 
Gulf of Mexico, 84-152 fathoms, “ Blake” Expedition (t. Dali). Off 
the coast of Europe, “ Porcupine ” Expedition; off Bermuda, “Chal- 
lenger” Expedition ; off’ the Azores, “Josephine” Expedition (t. 
Jeffreys, as N. curta). 
