1921] NATURAL SCIENCES OF PHILADELPHIA. 403 



Two smaller valves are nearly circular in outline. It becomes 

 oval with age, as Gabb remarked. 



ARCIDAE. 



Area umbonata Lamarck. 



Area itnhricala Briig., Gabb, Trans. Amer. Philos. Soc, xv, p. 254. 

 Area mnbonata Lamarck, Dall, Trans. Wagn. Inst., iii, p. 620. 



Characteristic specimens of this well known species are con- 

 tained in no. 2647. 



Area bonaezyi (Gabb) Plate XXXIX, figs, l, 2. 



Barbatia bonaezyi Gabb, Trans. Amer. Philos. Soc, xv, 1873, p. 254. 



This species stands very close to A. Candida Gmel., and a fuller 

 series may show that it is not separable. It differs by the narrower 

 form and very slight byssal sinuosity, which indeed is not visible in 

 the type valve, though noticeable in a smaller one. 



Length 34, alt. 18, diam. of right valve 7 mm. 



Type no. 2649 A. N. S. P. 



Area inaequilateralis Guppy. 



Area inaequilateralis Guppy, Q. J. Geol. Soc, xxii, 1866, p. 293, pi. 18, figs. 

 2a, b. 



Two specimens. It appears to be more abundant in the Bowden 



bed. 



Area (Seapharca) pennelli C^abb. Plate XXXIX, figs. 3, 4. 



A. {Anadara) pennelli Gabb, Trans. Amer. Philos. Soc, xv, 1873, p. 254. 



The type, a left valve, has 36 ribs. They are closely granose ex- 

 cept at the ends, where granulation is obsolete. The intervals 

 have sharp, irregular transverse striae. The cardinal area is narrow- 

 marked with a few waved longitudinal grooves, and defined by a 

 narrow strong keel. The hinge has a continuous tooth row of 16 

 and 35 teeth, irregular where the series meet. 



Length 36, alt. 27, diam. of left valve 13 mm. 



Type is no. 2651 A. N. S. P. 



In the right valve of another specimen the ribs are smooth. 



Area (Scapharea) sobrina Pils. and Johns. 



Proc. A. N. S. Phila. 1917, p. 186 

 = Area henekeni Maury. 



Area (Seapharca) eopiosa Pils. and Johns. 

 Proc. A. N. S. Phila. 1917, p. 186. 

 ^^ .4. margaretoe Maury. 



