Contributions to Invertebrate Palaeontology. 549 



Clionetes reversat 



Plate XI, figs. 8 aud 9. 



Chonetes reversa Wliitf., Ann. N. Y. Acad. Sci., 1882, 213, 



Shell of about a medium size, semicircular in outline, with a long straight 

 hinge-line exceeding the width of the shell below. Valves resupinate, or 

 reversed in their curvature ; the ventral being very slightly convex in the 

 earlier stages of growth, and subsequently recurved so as to appear concave ; 

 the entire deflection from a plane being very little, so that the general appear- 

 ance of this valve may be said to be nearly flat. Area linear. Hinge-line 

 ornamented by four, long, very slender spines on each side of the centre, which 

 are projected from the hinge-line at an angle of about 65 degrees, measured 

 on the outside; or 115 degrees as counted on the inside of the spine. Surface 

 of the ventral valve marked by exceedingly fine strije, which are slightly 

 alternating in size ; there being from two to five finer ones between the coarser 

 kind. Interior of the valve characterized by fine pustules, arranged in indis- 

 tinct lines, presenting the usual characteristics of the genus. Dorsal valve 

 not positively known ; but there is associated with it, in the same layers, a 

 slightly convex valve with similar strife, but more distinctly alternating, 

 which may possibly represent this valve. Its form is similar, and the con- 

 vexity correspondingly great. 



This species is peculiar in its resupinate character, so far as the 

 genus is known in American Devonian rocks, and this character, 

 together with its form, its fine striae, and its nearly erect slender 

 spines, will readily distinguish it from any other species. The 

 dorsal valve above spoken of was at first supposed to be the young 

 of Strophodonta perplana Conrad's sp., but the similarity in size 

 and character of striae to this species renders it doubtful. 



Formation and Locality. — In thin-bedded bituminous limestone, 

 from above the " Bone-bed" at Smith and Price's quarries, near 

 Columbus, Ohio, 



Genus SPIRIFERA Sowerby. 



Spirifera IHaia. 



Plate XI, fig. 14. 



Athyris Maia Billings, Can. .Jour. Ind. Sci. and Arts, May, 1860, p, 276. 

 Sperifera Maia (Bill.) Hall, Pal. N, Y., vol. 4, pt. 1, p. 416, pi. 63, figs. 6-13. 



Several single valves of this species have been obtained from the 

 thin-bedded limestones, associated with the Discina and Leiorhyn- 

 chus bearing shales, on Mr. Meeter's farm, two and a half miles 

 south of Dublin, Ohio; but in too imperfect a condition for illus- 



