458 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Class PELECYPODA. 
.Order PRIONODESMACEA. 
Superfamily NTJCULACEA. 
Family NUCULI1),£. 
Genus NUCULA Lamarck, 1799. 
Shell equivalve, closed, triangular, inequilateral, the posterior end short; beaks generally inclined 
to the rear; surface smooth or ornamentally sculptured; hinge with an internal, triangular fossette, 
containing a resilium and having on each side a row of sharp teeth; internal shell layer nacreous. 
Nucula aegeensis Jeffreys. 
Narnia xgeensis Jeffreys, P. Z. S., 1879, p. 581: Dali, Blake Report, I, p. 246, 1886. 
Shell rather small, thin, nearly regularly ovate, scarcely oblique, uniformly convex, and having 
a low, rounded posterior ridge; beaks projecting but little beyond the rest of the shell, straight; sculpture 
of exceedingly fine concentric ridges; hinge line rather broad; teeth few; cartilage pit small. 
Length, 10.7; height, 8; diameter, 4.7 mm. 
Mayaguez, Porto Rico, one young left valve. The species is close to N. tenuis Montagu. 
Family LEI MILE. 
Genus LED A Schumacher, 1817. 
Shell solid, oval-oblong, more or less beaked behind; beaks somewhat turned backward; surface 
concentrically and obliquely furrowed, with a posterior ridge or carina; hinge teeth numerous, similar 
fossette containing the resilium internal, placed below the beaks; pallia! line feebly sinuous; internal 
layer porcellanous. 
Leda acuta Conrad. 
Nucula acuta Conrad, Am. Marine Conch., p. 32, pi. vi, fig. 3, 1831. 
Shell inflated, irregularly long oval; anterior end rounded, but somewhat drawn out, with a ridge 
running from the beaks to the anterior base; posterior ridge strong, curved downward in the middle, 
the dorsal slope truncated and partly sunken so as to form a sort of escutcheon; beaks full, about two- 
tifths of the length of the shell from anterior end; sculpture consisting of fine, well-defined ridges, 
which are more or less concentric, but often oblique at the ends; hinge strong and wide, divided 
about midway by the fossette, with strong V-shaped teeth; interior of the shell shining. Color greenish 
olive. 
Length, 9; height, 5; diameter, 3.5 mm. 
Mayaguez Harbor, Porto Rico, a great number of specimens. 
The character of the sculpture is variable. In some specimens there are traces of cancellation in 
front. 
Genus NEILONELLA Dali, 1881. 
Shell inflated, the ends drawn out but rounded, with a single ligament directly between -the 
beaks, chiefly external, but its base dividing the hinge line while the upper surface extends about 
equally before and behind the beaks; teeth strong. 
Neilonella corpulenta Dali. 
Leda ( Neilonella ) corpulenta Dali, Bull. Mas, Zool., ix, 1881, p. 125; Blake Report, i, p. 254, pi. vn, figs, la, 15, 1886. 
Shell irregularly elliptical, inflated, solid, with rather high, full beaks; the posterior ridge low 
and close to the hinge; surface covered with well-defined, concentric ridges; hinge moderately strong, 
the posterior part a little longer than the anterior; teeth sharp, elongated, much reduced in size under 
the beaks; interior of the shell smooth and shining. 
Length, 10, height, 6.5; diameter, 4.5 mm. 
Mayaguez, Porto Rico, two opposite worn valves. 
