NO. 1985. NEW SPECIES OF SILURIAN FOSSILS— WILLIAMS. 329 



the lateral growth is double the length or even more and the number 

 of radii at the edge is less than 100. 



The form I name C. cohscooiki is very close in outline to the Waldron 

 form figured by Hall as C. nova scoticus, is somewhat larger, but shows 

 evidence of at least 4 and sometimes 5 spines on each side. It is not 

 "more ventricose than C. comuta," but in some specimens is less so 

 than seen in examples from the Chnton formation of New Hartford. 

 The striae are frequently bifurcated two or three times in course of 

 their growth and reach a greater number than 100 at the front 

 margin. 



Genus BRACHYPRION Shaler. 



BRACHYPRION SHALERI, new species. 



Plate 29, figs. 10, 11, 12. 



Shell of medium size, flat, semielliptical, wider than long, greatest 

 width at cardinal edge. Pedicle valve slightly convex throughout its 

 growth, brachial valve slightly concave. Surface ornamented by 

 elevated thread-like radii of two sizes, the larger about 20 near beak 

 and increasing to about 50 at the front, between which are finer lines 

 becoming 5 to 8 in central shell, but one of them rising to strength of 

 the primary radii divides them mto 4 or 5 small between each large 

 radii near the front border. The cardinal border is crenulated each side 

 the middle for a third the distance to end of hinge line. The dental 

 lammge of the pedicle valve are strong and continued as slightly 

 diverging ridges each side the muscular scar, about one-third the 

 length of the shell. A linear median septum of about the same length 

 divides the muscular scar into two lobes. The ridges from the outer 

 face of the dental sockets of the brachial valve are strong; from the 

 inner side of each proceeds forward a strong Imear ridge, curving 

 gently outward and extending halfway to the front, the two bounding 

 the muscular scars. 



The species closely resembles 'Stroplionella striata (Hall), but differs 

 from it in being convexo-concave throughout growth, showing no 

 tendency to resupination. The shell is not perfectly symmetrical in 

 its convexity, showing in some specimens of the pedicle valve slightly 

 greater convexity on one side than the other, but m no specimen is 

 reversal to concavity exhibited in course of growth, which feature 

 excludes it from the genus StropTionella. The type-specimens are 

 from tjie west shore of Cobscook River, south of Ball's Mountam, in 

 Edmunds Township (localities 8. 2 1.1 A and 5.51.5B). 



Specimen No. 1414.3 (pi. 29, fig. 12), an interior mold of a brachial 

 valve, shows that valve to have been concave, and exhibits the charac- 

 ters of the central part of the shell in mold. Comparison with figures 

 4 and 8 of the same plate w^ill show the differences between the brachial 

 valve of this species and Leptostrophia. 



