NATURAL SCIENCES OF PHILADELPHIA. 187 
Genus STENOGYRA, Shuttl. 
I have not been able to examine S. octonoides (S. subula of L. 
and Frw. Shells, I.) or S. gracillima, but only S. decollata, Lin., 
from Charleston,’ S. C., a species introduced from Europe by 
commerce, and the true S. subula found near Mobile, Ala. Of 
extralimital species I have examined S. octona, gonostoma, and 
hasta. Semper has examined S. Panayensis. 
The jaw (see pl. XVI., fig. 1, for that of S. subula) is low, wide, 
with attenuated, blunt ends, and a wide, slightly produced median 
projection. There are distinct vertical strize on that of S. 
decollata. 3 
The. lingual membrane is long and narrow. The central tooth 
has a very small, high, narrow base of attachment, the lower outer 
angles generally somewhat expanded. The reflected portion is 
very small, and bears a short, stout, median cusp, and two very 
small side cusps; all the cusps bear distinct cutting points. The 
lateral teeth are very much larger than the centrals. The base of 
attachment is about as high as wide, its inner lower lateral expan- 
sion suppressed as usual. The upper edge is squarely reflected. 
The reflection is very large, and bears one stout median cusp, 
extending almost to the lower edge of the base of attachment ; 
there is also an outer, much smaller side cusp, and a less devel- 
oped, sometimes subobsolete inner side cusp; all the cusps have 
distinct cutting points, proportioned to their size; that on the 
central cusp being greatly developed. In S. decollata (pl. XV., 
fig. 5) the inner cutting point is also much developed, and joined 
to the central cutting point. The marginal teeth in S. decollata 
are but a modification of the laterals, with the suppression of the 
inner cusp and cutting point (6); the extreme marginals (c) differ 
in the greater development of the reflected portion and equaliza- 
tion with it of the cutting points, of which there are but two. In 
S. subula (pl. XV., fig. 8) the marginal teeth (0) have more nu- 
merous cutting points, formed by the bifurcation of the inner and 
outer cutting point. The second denticle from the inner side is 
the largest. It will be noticed that in S. decollata both the side 
cutting points of the laterals are quite thorn-shaped. 
S. decollata, L. (pl. XV., fig. 5, b is one of the first marginals, 
1 T found the species in great numbers at various localities in this city 
during a recent visit (1875). 
