356 Systematic Paleontology 



narrower and far broader, and its lingual anterior extension far less in- 

 flected, while the plications on the lateral portions of the dorsal valve are 

 more sharply angular. In other words, the characters of this species are 

 those of C. speciosa, and it is undoubtedly the transitional form between 

 0. camphellana and the characteristic Oriskany Plethorhyneha. It differs 

 from C. speciosa in never attaining more than one-half its size, the ventral 

 sinus is more pronounced, being broad and more or less undefined, and 

 the plications are more constant in number, there being from thirty-two 

 to thirty-six in each valve in the Covington, Virginia, specimens. In 

 addition C. praspeciosa is found at a lower horizon, i. e., in the Becraft 

 zone, while C. camphellana occurs in the New Scotland zone of the Helder- 

 berg formation. Two dorsal interiors found by Eowe show the internal 

 characters of Plethorhyneha. 



Length 3.5 cm. ; width about 3 cm. 



The writer has many specimens of Uncinulus nohilis from the Becraft 

 of Schoharie County, New York, none of which approach C. proispeciosa, 

 but curiously a single specimen apparently from the Becraft zone of 

 Becraft Mountain (Jones's Quarry), near Hudson, New York, is of this 

 species. It has the flat and very broad ventral sinus and sharply angu- 

 lated sides of the Maryland forms. 



Occurrence. — Helderberg Formation, Becraft Member. Ernstville, 

 Maryland; two miles "below" (probably northeast, along the railroad) 

 Covington, Virginia. 



Collections. — Maryland Geological Survey, U. S. National Museum. 



Camarotcechia (Plethorhyncha) speciosa (Hall) 

 Plate LXIII, Figs. 22-27 



Rynchonella speciosa Hall, 1857, Tenth Ann. Rept. N. Y. State Cab. Nat. 



Hist, p. 81. 

 Rhynclwnella speciosa Hall, 1859, Nat. Hist. N. Y., Pal., vol. iii, p. 444, pi. 



ciiia, figs. 1-6, 1861. 

 PlethorJiyncha speciosa Hall and Clarke, 1893, iMdem, vol. viii, pt. ii, p. 191, 



pi. Iviii, figs. 29-37. 



Description. — " Shell longitudinally ovoid, vertically flattened on the 

 sides, higher than wide, abruptly rounded or subtruncate in front ; sides 



