22 
PROCEEDINGS OF THE ACADEMY OF 
Its closest analogue is M. primigenius, Hall, (Io. Rep. p. 720, pi. xxix. 11.) 
j|= M. ponderosus, Swallow, (Trans. Acad. Sci., St. Louis, i. p. 202). The aper¬ 
ture, however, is broader, the spire less elevated and the columellar fold ap¬ 
parently much less pronounced. 
From the lower bed of the yellow sandstones—being, until the recent de¬ 
scription of some specimens from the Hamilton Group of New York, (See Fif¬ 
teenth Rep. N. Y. Reg., p. 48), the lowest known position of this section of 
the genus. 
LOXONEMA, Phillips. 
Loxonema oligospira, n. sp.—Shell small; whorls about six, rather rapidly 
enlarging, convex exteriorly, with traces (on the cast) of vertical ridges, which 
become most observable in the vicinity of the aperture; suture deep ; body 
whorl three-fifths the length of the shell, more rapidly enlarging than the 
spire, gently convex on the outer side, more rapidly curved toward the base 
—which is somewhat umbilicately indented—rapidly increasing in diameter 
toward the aperture, which is thus rendered somewhat effuse in front. 
Height of shell *41 (100) ; height of body whorl *25 (61) ; diameter of body 
whorl *29 (71) ; diameter of penultimate whorl *16 (39). 
HOLOPELLA, McCoy. 
PIolopella mira, n. sp.-—Shell small, turrited; whorls gradually and regu¬ 
larly enlarging, seven or eight in number, of which four or five are generally 
preserved,—the apical ones, in numerous specimens, uniformly wanting; 
whorls sometimes slightly flattened on the exterior; suture distinctly but not 
deeply impressed ; body whorl regularly rounded beneath into a minute um¬ 
bilicus ; aperture nearly circular, obtusely angulated behind, regularly rounded 
in front; peristome complete or slightly interrupted; columellar lip without 
a fold, very slightly excavated by the aperture. 
Height of shell about -24 (100); height of body whorl *11 (46) ; diameter 
of body whorl *14 (58) ; apical angle 35°. 
This little shell occurs gregariously in calcareous layers of bed No. 3, and 
also occasionally in sandstone No. 5. The exterior seems to be destitute of 
natural ornaments, but the specimens in bed No. 3 are universally marked by 
lines like cleavage cracks, running very obliquely across the several whorls,— 
their lower extremities being nearest the aperture. 
This fossil bears a close resemblance to Turritella (Holopella ) gregaria and 
conica , Sow., (Murch. Sil. Syst., pi. iii. fig. 1, f. and 8) from the old Red Sand¬ 
stone, but it differs from both (See McCoy, Pal. Foss., p. 303,) in apparently 
having no natural surface markings. 
NATICOPSIS, McCoy. 
Naticopsis depressu^, n. sp.—Shell small; spire of about four volutions, 
scarcely elevated above the body whorl; last whorl rapidly enlarging, espe¬ 
cially in an obliquely transverse direction ; suture very shallow, giving the 
upper side of the shell a general convexity; width of last whorl at the aper¬ 
ture three-fifths the transverse diameter of the shell; aperture oval, rounded 
anteriorly and posteriorly; within, somewhat contracted on the inner side by 
the broad, flattened columella ; surface marked by delicate lines of growth, 
which, toward the suture, become, on the last whorl, fine, regular, elongated 
nodes. Highest point of shell, when resting on its base, is on the last whorl, 
near the junction of the outer lip with the penultimate whorl. 
Height of shell from antero-lateral margin of aperture obliquely to summit 
of spire *50 (100) ; greatest transverse diameter *59 (118) ; width of body 
whorl measured in the same direction *36 (72) ; altitude of shell when resting 
on its base, in a direction nearly at right angles with the last measure *30 
(60) ; length of aperture *37 (74) ; width *32 (64). 
ORTHOCERAS, Breynius. 
Orthoceras Whitei, n. sp.—Shell annulated, very gradually tapering, with 
[Jan. 
