MARYLAND GEOLOGICAL SURVEY 341 



sculpture, the inner margins more finely crenulate or even smooth, 

 lunule shorter and wider, and the posterior dorsal area narrower and 

 more ventrical than in P. crenulatus. Alt, 6.5, Ion., 7.0, diam., 4.0 mm. 



" The beaks are much more prominent and more recurved over the 

 small globular lunule, the ribs are wider than their interspaces, and the 

 radial structure is seen only when the shell is decoricated." Dall, 1903. 



Occurrence. — St. Mary's Formation. St. Mary's Eiver. Calvert 

 Formation. Plum Point. 



Collection. — U. S. National Museum. 



Subgenus LUCINISCA Dall. 



Phacoides (Lucinisca) cribrarius (Say). 



Lucina cribraria Say, 1834, Jour. Acad. Nat. Sci. Pbila., vol. iv, 1st ser., p. 147, pL 

 xiii, fig. 1. 



Lucina cribraria Conrad, 1843, Proc. Nat. Inst., Bull, ii, p. 187. 



Phacoides (Lucinisca) cribrarius Dall, 1903, Trans. Wagner Free Inst. Sci., vol. iii 

 pt. vi, p. 1372. 



Description. — The type specimen of this species has been generally 

 thought to come from St. Mary's County, Maryland. The author knows 

 of no authentic specimen from Maryland in any collection, notwith- 

 standing the extensive collections which have been made by the Mary- 

 land Geological Survey. He is of the opinion that Say's type really 

 came from Virginia. 



Occurrence.— ^T. Mary's Formation. St. Mary's River. (Con- 

 rad). 



Genus DIVARICELLA von Martens. 



Divaricella quadrisulcata (d'Orbigny). 



Plate XCV, Fig. S. 



Tellina divaricata Dillwyn, 1817, Cat. Rec. Sh., i, p. 103 {ex parte), and of many 



other authors. 

 Lucina quadrisulcata d'Orbigny, 1846, Voy. Am. Mer., p. 584. 

 Divaricella quadrisulcata Dall, 1903, Trans. Wagner Free Inst. Sci., vol. iii, pt. vi, 



p. 1389, pL li, fig. 1. 



Description.— This species has been listed from Maryland but the 

 author knows of no authentic specimen in any collection and has failed 

 to find it himself. Say's specimen of this species is also believed to 

 have come from Virginia. 



