New Lamellibranchiata — Ulrich. 283 
about 150 ft. above the Ohio river. A specimen, represented in the cut 
by o, 6 and c, was lately collected in the "Modiolopsis bed" of the 
Trenton near Burgin, Ky. 
Modiolopsis angustata, n. sp. 
Fig. 10, Modiolopsis angustata, n. sp., lower beds of the Cincinnati 
group, at Covington, Ky. a, b, and c, three views of a specimen of this 
species. 
Shell small, elongate, a little the widest posteriorly, the 
length equal to two and one-half times the greatest width. Car- 
dinal and basal margins nearly straight, sub-parallel. Anter- 
ior end contracted in front of beaks, somewhat extended, with 
the extremity curved abruptly. Posterior end convex, the up- 
per half rounding gently into the cardinal margin, the lower 
half the most prominent and with the curve more pronounced. 
Beaks short, flattened, slightly incurved, situated about one 
fifth of the entire length of the shell from the anterior extrem- 
ity. Body of shell moderately convexed, with a but slightly 
developed umbonal ridge ; central portion flattened from the 
beaks to the basal margin, not enough however to cause the 
latter to become sinuate. Point of greatest convexity a little 
above the center of the shell, cardinal slope, very slightly 
convex or flat. Surface marked with small irregular concen- 
tric furrows, strongest centrally, and much finer lines between 
them. 
Length 23.5 mm. ; greatest hight (at posterior extremity of 
hinge line) 9 mm. ; hight at beaks, 7 mm.; convexity of the 
two valves in conjunction, 6 mm. 
This species resembles Oi'thodesnia in its elongate form and 
unusually extended (for Modiolopsis) anterior end. In all 
other respects however, it agrees very well with typical species 
of this genus. 
The New York Trenton species M. mytiloides Hall, (Pal. N. 
Y. vol. I, p. 157, PI. 35, fig. 4) may be a closely related species. 
The figures show it to be a more convex shell, with shorter an- 
