201 



Chonetes mucronatus. Hall. (Fig. 105.) (Pal. N. Y., 

 Vol. IV.. p. 125, Pis. XX., XXI.) 



Distinguishing Characters. — Small size; semi-oval outline; 

 moderately convex character; rather distant and strong, 

 radiating, rounded or sub-angular strife, which are not as 



P 



'*«../ y' ,v 



Fig. 105. Chonetes mucronatus. Pedicle valve, natural size and enlarged, with profile 

 of same; enlargement of another specimen, dorsal view (from Hall). 



wide as the spaces between them (or are more or less closely 

 crowded) : abruptly outward-curving cardinal spines, of 

 which there are two, or rarely three, on each side. 



Found rarely in the upper Moscow shale, below the tran- 

 sition beds; in the lower Moscow shale, at Sections 4- and 5 

 (not very common) ; Encrinal limestone ( var. laticosta), at 

 Section 5 (rare) ; shale below the Trilobite beds, in Avery's 

 Creek (rare); Pleurodictyum beds (rare); Transition shales, 

 in Erie and Athol Springs Cliffs (rare) ; Marcellus shales, in 

 Athol Springs and Bay View Cliffs (rare). 



Chonetes vicinus. (Castelnau.) (Fig. 106.) (Chonetes 

 defiectus. Hall. Pal. X. Y., Vol. IV., p. 126, PI. XXI. ) 



Distinguishing Characters. — Semi-elliptical outline ; strong 

 convexitv; deflected cardinal margins (as seen from the con- 



Fig. 106. Chonetes vicinus (deflectus). Ventral, dorsal and profile views of a charac- 

 teristic specimen, natural size: enlargement of interior of a brachial valve, showing cardi- 

 nal process and muscular impressions (from Hall). 



vex side) ; abruptly outward-curving cardinal spines ; finer, 

 more numerous, and more closely crowded stria than occur 

 in C. mucronatus. 



