Mauyland Geological Survey 173 



Oldtowii; on Jvoiniiey-Hanging- Rock Eoad about Vo iiulc north of T?om- 

 ney, W. Va. ( ?) : B. & 0. H. E. cut at TIancock Station, W. Va. ( ?)• 



Collections. — Maryland Geological Survey; New York State Museum; 

 American Museum of Natural History. 



Camarotoectiia trolifica Hall 

 Plate XY, Figs. 1-;^ 



Rliynchonella (Stenocisnia) prolifica Hall, 1867, Pal. N. Y., vol. iv, p. 343, 



pi. llv A, figs. 1-10. 

 Stenoschisma prolifica Koyes, 1891, .Johns Hopkins Univ. Circ, vol. xi, p. 29. 

 Camarotoechia prolifica Hall and Clarke, 1893, Pal. N. Y., vol. viii, pt. ii, 



p. 192, pi. Ivii, figs. 42, 43. 

 Camarotoechia prolifica Schuchert, 1897, Bull. U. S. Geol. Surv., No. 87, p. 168. 



Description. — Shell subtriangular-ovate : length and width about equal; 

 front rounded, with a shallow sinus and gentle elevation, depressed in 

 young shells and becoming gibbous in older ones. A^entral valve depressed- 

 convex in the middle, elevated or a little gibbous on the umbo, curving to 

 the sides and with a shallow sinus below the middle; apex slightly in- 

 curved. Dorsal valve equally convex with the ventral, sometimes a little 

 more convex ; Ijelow the middle of the valve the mesial fold becomes more 

 or less elevated, but rarely rises conspicuously above the general outline; 

 in the interior is a short septum. Surface marked by from about twenty 

 to twenty-four angular plications, of which three occupy the mesial sinus 

 and four the mesial fold. 



A partly covered and more or less exfoliated ventral valve from a cal- 

 careous layer in West Virginia, opposite Madders Island, four miles south 

 of Cumberland, is referred to this species as well as specimens from other 

 localities. The plications are fully as small and angular as those repre- 

 sented in the figures of New York specimens and rather more numerous 

 than on some of them with which they have been compared ; there are 

 three plications in the sinus, and the valve is rather more convex in the 

 middle than in specimens from arenaceous shales. This species is dis- 

 tinguished by its shape, slender angular plications, and sliallow sinus with 

 three plications. 



Length, 9 mm. ; width. 8 mm. of Potomac Eiver specimen. 



Occurrence. — Rojeney' FoRiiAxiox, Oxondaga Member. B. & 0. E. E. 

 cut at 21st Bridge ( ?). HA:\[iLToy Member. B. &. 0. E. E. cut at 31st 



