198 



Found in the lower Moscow shales, ;it Sections 4 and .~> 

 (common); Encrinal limestone at Section .*> (common); 

 Stictopora and Demissa beds, at Section 5 (common); shales 

 between the Demissa and Trilobite beds, at Sections (> and 7 

 i Frequeul ) ; Trilobite beds, at Section 8, and in Avery's Creek 

 (rare); shales below the Trilobite beds, on the Lake Shore 

 and in Avery's Creek ( occasionally) ; Pleurodictyum beds, in 

 Avery's Ravine (rare); shale below the Nautilus bed (not 

 uncommon). 



STROPHEODONTA I DONVILLINA ) INJEQUISTRIATA. (Conrad. ) 



(Fie. KH.) (Pal. X. Y.. Vol. IV.. p. 106, PI. XVIII.) 



Distinguishing Characters. — Small size; considerable con- 

 vexity of pedicle valve; extended hinge line with acute, 

 sometimes auriculate, extremities ; surface marked by distant 



I'i<;. in]. 8trppheodonta incequistriata. Lateral and dorsal views of two specimens: 

 three pedicle valves; interior of a brachial valve, showing cardinal process and muscular 

 impressions I from Hall I. 



stria-, with finer, almost invisible, striae between: in the 

 brachial valve the bifid cardinal process is supported by a 

 ridge, which divides anteriorly and encloses a muscular area. 

 For I he a1 tachmenl of the anterior adductors. 



Found in the Moscow shales, three to five feet above the 

 base, a1 Sections 4 and 5 (common); Encrinal limestone, at 

 Section •"> (rather rare): Stictopora bed, at Section 5 (fre- 

 quenl I: Demissa bed.. -it Section 5 (very common) ; Trilobite 

 beds. ;it Section 8, and on the Lake Shore (occasionally): 

 shale and limestones bet ween the Trilobite and Strophalosia 

 \n-i\s. on the Lake Shore and in Averv's Creek (occasionally). 



