174 
PALAEONTOLOGY OF NEW-YORK. 
This species, in form, bears considerable resemblance to the one cited above ; but it is 
uniformly smaller, more distinctly striated, and has the spire more elevated, with the 
volutions vertically elevated at the sutures. The umbilicus is also smaller than in E. qual- 
teriatus , and the outer margin less nearly vertical. It is distinguished from the preceding 
species, with which it has usually been confounded, by the greater elevation of the spire 
and the convexity of the volutions, and also in the form of the aperture, which is nearly 
subquadrate. It is a very neat symmetrical species, occurring much more rarely than the 
P. lenticularis. 
Fig. 7 a. View of the aperture and front of the shell, showing the elevation of the spire. 
Fig. 7 b. View of the top of the spire. 
Fig. 7 c. View of the base, showing the umbilicus. 
Position and locality. In the lower part of the Trenton limestone at Middleville. 
225. 13. PLEUROTOMAR1A SUBCONICA ( n. sp.). 
Pl. XXXVII. Figs. 8 a, b, c, d, e. 
Compare Trochus ellipticus, Hisinger, Leth. Suecica, pag. 35, pi. 11, fig. 1. 
— tro chifor mis. Forelock, Geol. Rep. Londonderry, 1843, pag. 414, pi. 30, fig. 9. 
Trochiform ; spire elevated, apex acute ; volutions about five, flattened above, with a 
projecting carina just above the suture ; last volution strongly carinated on the outer edge, 
and marked with a spiral band, ventricose below ; aperture transverse, subquadrate, an¬ 
gular on the outer side and round below ; surface marked by fine striae, which bend gently 
backwards from the suture, and more abruptly on the lower part of the whorl ; spiral band 
a distinct groove, margined by sharp elevated edges, upon which the striae bend backwards 
in an abrupt curve ; below this the striae bend gently forward, and thence curving back¬ 
wards, terminate in the umbilicus; longitudinal striae crossed by transverse sharp elevated 
lines which are finer than the longitudinal ones. 
This is a beautiful trochiform shell, with a symmetrical conical spire, and beautifully 
cancellated surface. The finer concentric striae are often obliterated from wearing or ma¬ 
ceration, the longitudinal ones only remaining, and these also are often obliterated. The 
spiral band is distinct on the last volution, and the striae upon it appear to be crowded into 
ridges. The suture is formed just at the lower margin of the band, leaving it visible at the 
lower edge of the higher volutions. In casts of this species, the outer angle of the last 
volution is distinctly carinated, as also the lower margin of the higher volutions. 
Fig. 8 a. Front view of a specimen preserving the shell in a very perfect manner; the aperture im¬ 
perfect. 
Fig 8 b. Base of the same, showing the small partially closed umbilicus. 
Fig. 8 c. An enlarged portion of the surface, showing the cancellated strife which are scarcely visible 
to the naked eye. 
Fig. 8 d. Cast of another specimen. 
Fig 8 e. Front view of the same, showing the form of the aperture. 
