353 lyiGNiTic Stage 6i 



concentric lines about the umbones, becoming rugose and la- 

 mellar posteriorly ; teeth sometimes becoming obsolete in old 

 specimens but when well preserved showing in the left valve 

 one strong, nearly horizontal cardinal tooth, with a deep pit 

 on either side ; right valve with two cardinal teeth as shown 

 in the figure ; pallial sinus not deep but well defined ; numer- 

 ous traces of radiating striae. 



The dentition of this species seems to be precisel}^ that of 

 C. lithophagella Lam., neither have any lateral, teeth worthy of 

 the name. On the other hand the pallial sinus is far too 

 deep for this genus, and approaches that of Petricola. The 

 radiating striae also recall the latter genus. That it was a 

 boring shell, I have no doubt. 



Locality.- — -Alabama: Found abundantly in the indurated, 

 bluish, fossiliferous, thin ledges in Hatchetigbee 

 Bluff. A fragment of a very large specimen, 

 probably of this species, is in Harris' collec- 

 tion from Gregg's lyanding. 



Type. — Paleontological Museum, Cornell University. 

 Meretrix nuttalliopsis, Pl. 12, fig. 5. 



Syn. Cytherea nuttalliopsis Heilp., Proc. Acad. Nat. Sci. Phila., 1880, 

 p. 370, pi. 20, fig. I. 

 C. nuttalliopsis Aid., Bull, i, Geol. Surv. Ala., pp. 53-57. 

 ? C. miniina Aid., Bull, i, Geol. Surv. Ala., pp. 53-57. 



Heilprin'' s original description. — "Shell sub- elliptical, moder- 

 ately ventricose, its surface covered with fine concentric striae, 

 which are apt to become roughly imbricate on the basal mar- 

 gin ; umbones not very prominent, rather anterior ; lunule 

 cordate, deeply impressed at about its middle, its outline clear- 

 ly pronounced by a sharply impressed line ; posterior extrera- 

 it}^ regularly rounded, the anterior somewhat produced ; margin 

 entire ; pallial sinus somewhat angular, pointing towards the 

 center of the shell. 



"Length, ij^ inch. Knight's Branch, Charke Co., Ala. 



"This species most resembles among American species of 

 Cytherea the C. nuttalli Con., from which it may be distin- 

 guished by the greater production forward of the anterior ex- 

 tremity, and by the median depression in the lunule. In this 

 last charadler it agrees with C. poulsoni Con., from which, 

 however, it verj' materially differs in form, and in the much 



