Kkede.| Carboniferous Invertebrates. 69 



muscular impressions, with numerous, rather distinct granules, 

 arranged in radiating rows — immediately within the fissure, 

 provided with a short, rather prominent, compressed ridge 

 ranging at right angles to the hinge ; muscular impressions 

 very obscure. 



" Dorsal or concave valve, following nearly the curve of the 

 other; area of about the same size as in the dorsal | ventral j 

 valve, inclined forward from the hinge; cardinal process small, 

 not very prominent, and, as seen on the outer side, somewhat 

 trilobate, the middle lobe or ridge being divided by a linear 

 sulcus ; socket ridges very oblique ; interior granulated as in 

 the other valve. A very small, obscure linear ridge occupies 

 the middle of the valve, without, however, extending up to the 

 hinge ; muscular impressions unknown. 



• Surface of both valves nearly smooth, but showing obscure, 

 concentric marks of growth. In some conditions of weathering 

 there is a faint appearance of radiating markings, but this is 

 due rather to the structure of the shell and not to proper ex- 

 ternal lines. When a single one of the thin valves is cleaned, 

 and examined by the aid of a good magnifier and a strong trans- 

 mitted light, very scattering punctures or pores are seen arranged 

 in quincunx, and passing obliquely through the shell. These 

 appear to have been connected with minute tubular spines, 

 arranged over the whole surface, during the life of the animal." 



Range and distribution : Upper Coal Measures; Topeka. 



Chonetes granulifer. Plato IX, fi^s. 1-lc. 



Chonetes granulifera Owen, Geol. Rep. Iowa, Wis., and Minn., p. 583, 



tab. v, f. 12, (1852); Meek, Fin. Rep. U. S. Geol. Surv. Neb., p. 171, pi. 



iv, f. 19, pi. viii. f. 8, (1872); etc. 

 Chonpfes smithii Norwood and Pratten, Jour. Acad. Nat. Sci. Phil., in, 



p. 24, pi. ii, f. 2, (1854); oto. 

 Chonetes mucronata Meek and Haydeo, Pino. Acad. Nat. Sci. Phil., p. 



262, (1858); Pal. Upp. Mo., p. 22, pi. I, f. 5, I 1864); etc. 

 Chonetes granuliferus Beechor. Am. .lour. Sci., 3d ser., xli. p. 357, pi. 



xvii, f. 15, (1891). 

 Chonetes granulifer Schuchert. Bull. ST. V. S. Geol. Surv., ( 1897). 



Meek's description: "Shell attaining a rather large size, 

 semicircular in outline, having its greatest breadth on the 

 hinge line, which often terminates in extended mucronate ears. 



