NATURAL SCIENCES OF PHILADELPHIA. 
419 
making with the former an angle of 88 c to 91° ; ventral border sub-circular. 
Beaks prominent, acute, direct, incurved. Anterior hinge plate with about 
17 teeth; posterior with about 13, much smaller. Adductor scars subterminal, 
profound, roundly oval. Surface of casts perfectly smooth. 
Length -86 (100); height *74 (86); thickness *44 (51); distance form beak 
to line joining extremities *40 (46) ; length of anterior end ’51 (59); of pos¬ 
terior end *35 (41). 
Locality. —Battle Creek and Grindstone Quarries, Pt. aux Barques. 
Nuctjla Stella, n. sp.—Shell very small, elliptic-ovate, with subcentral 
beaks. Anterior cardinal slope arched, posterior nearly straight; extremities 
rather sharply rounded ; ventral side semi-elliptic. Anterior hinge plate with 
17 minute, acute teeth ; posterior with 5, angulated in both cases towards the 
beak. Beaks a little attenuated near the extremity, curved inwards and 
backwards. Pallial line entire, connecting the muscular scars, which are 
oval, and situated considerably above the middle line of the shell. Shell 
thin, with delicate concentric striae. 
Length *33 (100); height *24 (73) ; thickness *14 (42) ; length of anterior 
end *20 (61); of posterior end *13 (39); distance from beak to line adjoining 
extremities *14 (42). 
Localities. —At every outcrop of the formation in the southern part of the 
State. Also at the Grindstone Quarries, Pt. aux Barques. 
This beautiful little shell has affinities with N. ventricosa, Hall, (Iowa Rep. 
716, pi. 29, fig. 4), from the coal measures of Iowa. It is easily mistaken for 
the young of N. Hubbardi, but is proved distinct by its more rounded sides 
and fewer teeth, as well as by its occurrence in a region of the State where the 
larger species is as yet unknown. 
Leda, Schumacher. 
Leda bellistriata, Stevens (Sill. Jour. [2], vol. xxv., p. 261).—Shell small, 
twice as long as high, somewhat ventricose, with sub-central beaks, which 
are rather prominent, incurved and pointed forward. Anterior cardinal slope 
slightly convex, posterior concave, with a well defined, long, deep and nar¬ 
row escutcheon; anterior extremity broadly rounded; posterior attenuate, 
With a blunt termination. Angle of the cardinal line between the beaks 130°. 
Surface marked by regular sharply-impressed concentric striae, of which 45 
may be counted between the ventral margin and a point one-tenth of an inch 
below the beak, where they become undistinguishable. Striae not visibly ex¬ 
tending across the escutcheon. 
Length *61 (100) ; height *34 (56) ; thickness *18 (29) ; length of posterior 
end *38 (62); of anterior end *23 (38); height of beaks above line connecting 
extremities *17 (28). 
Locality. —Moscow, Hillsdale county. 
I see no means of separating our species from the one described by Stevens 
from the coal measures of Ohio. Prof. Hall’s specimens from Iowa, however, 
which he has referred to the same species, differ from ours in a broad escut¬ 
cheon, and the continuation of the striae across it, characters which are stated 
not to exist in the original specimen. 
A rostral extremity of a Leda, from Battle Creek, marked and proportioned 
as above, is *64 long and *59 high, and by the principles of proportion must 
have belonged to an individual nearly 1^ inches long. 
Cardium, BruguRre. 
Cardium Napoleonense, n. sp.—Shell small, truncately triangular, oblique. 
Beaks elevated above the hinge, prominent, sharp, direct; hinge-line anterior 
to beak, short and straight, forming a rounded anterior angle with the ventral 
border, which sweeps by a regular course to the posterior border, which is 
elongate, truncate at right angles with the hinge-line, and furnished with a 
1862 .] 
