NATURAL SCIENCES. OF PHILADELPHIA. 419 



making with, the former an angle of 88 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 jdning extremities -40 (46) ; length of anterior end '51 (59); of pos- 

 terior end *35 (41). 



Locality. Battle Creek and Grindstone Quarries, Pt. aux Barques. 



Nucula 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 stride. 



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 ventrieose, with sub-central beaks, which 

 are rather prominent, incurved and pointed forward. Anterior cardinal slope 

 slightly convex, posterior eoncave, 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. Stria? 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 stria? 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, Bruguiere. 



Cardium Napoleonexse, 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.] 



