146 [Senate 



In some respects tbis shell resembles C. nana, but the striae are more 

 regular and stronger : in the only specimens I have seen showing the spines, 

 these appendages are directed outwards almost at right angles to the lon- 

 gitudinal axis of the shell. It is barely possible, however, that this may be 

 due to accident. In the oblique direction of the spines, it resembles C. 

 koninckana of Norwood and Pratten ; but it differs remarkably from 

 that shell, in the greater convexity of the ventral valve : it also has more 

 numerous striae, etc. A rare species. 



Geological "position and locality. Hamilton group : York, Livingston 

 county. 



Chonetes CORONATA. 



Strophomena carinata (Scr. coronata), Conrad, 1842 : Jour. Acad. Nat. 



Sci. Phil. Vol. viii, p. 257. 

 Not S. carinata, Conrad : Rep. Pal.N.Y. 1839, p. 64. 



Compare C.tuomeyi, Norwood and Pratten. Jour. Acad. Sci. Phil., Yol. 



iii, new ser., pa. 30, pi. 2, f.9. 



Shell transversely oval or nearly semicircular ; hinge not quite 

 equalling the greatest breadth, obtusely angular at the extremi- 

 ties : dorsal valve concave; area narrow and inclined obliquely 

 towards the front of the shell, having in the middle a small but 

 projecting dental process : ventral valve convex, most gibbous 

 in the central and umbonal regions, depressed at the extremities, 

 sometimes faintly sinuate down the middle ; beak small, and 

 scarcely projecting beyond the cardinal margin ; area rather 

 narrow, distinctly arcuate ; foramen small, broadly triangular, 

 generally closed by a convex deltidium, and occupied below 

 by the prominent dental process of the other valve ; cardinal 

 margin having five tubular spines on each side of the beaks, the 

 lateral of which is removed from the extremity of the hinge, 

 and those nearest the beak are very small or mere granules. 

 Surface ornamented by aistinct elevated strise, of which about 

 fourteen may be counted near the beaks, but which bifurcate 

 as they approach the front, so that the number is increased to 

 about one hundred at the border (on large specimens) : crossed 

 by extremely fine closely arranged concentric strise. 



This species agrees exactly with Conrad's figure and description of 



