DESCRIPTIONS OF SPECIES. 357 



1900. Chonetes granulifer. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 69, pi. 9, figs. 1-lc. 



Coal Measures: Common throughout Coal Measures; from Kansas City to Topeka and Manhat- 

 tan, Grand Summit, etc., Kans. 

 1900. Chonetes granuUfera. Knight., Univ. Wyoming, AVyoming Exp. Sta., Bull. No. 45, pi. 3, fig. 2. 



In all the collections examined but a single specimen of this form, so common at 

 certain horizons in the Mississippi Valley, has come to hand. It seems, however, to 

 be a characteristic example of Owen's well-known species. 



Locality and horizon. — Dolores River region, Sinbads Valley (station 2285); top 

 of the Hermosa formation. 



Chonetes mesolobus Norwood and Pratten. 



PI. I, figs. 20, 21, 22, 23. 



1855. Chonetes mesoloba. Norwood and Pratten, Acad. Nat. Sci. Philadelphia, Jour. (2), vol. 3, p. 27, 

 pi. 2, figs. 7a-c. 

 Coal Measures: Belleville, 111.; Charboniere, Mo. 

 1875. ChoneUs mesoloba. White, U. S. Geog. Geol. Surv. W. 100th Mer., Rept., vo). 4, pt. 1, p. 123, 

 pi. 9, fig. 7a. (Entire volume published in 1877.) 

 Carboniferous: Confluence of White Mountain and Black rivers, Arizona. 

 1883. Chonetes mesoloba. Hall, Rept. New York State Geol. for 1882, pi. (16) 47, fig. 22. 

 Coal Measures. 



1887. Chonetes mesoloba. Herrick, Sci. Lab. Denison Univ., Bull., vol. 2, p. 49. > 

 Coal Measures: Flint Ridge, Ohio. 



1888. Chonetes mesoloba. Keyes, Acad. Nat. Sci. Philadelphia, Proc, p. 228. 

 Lower Coal Measures: Des Moines, Iowa. 



1892. Chonetes mesoloba. Hall and Clarke, Int. Study of Brach., pt. 1, pi. 20, fig. '7. 



Coal Measures: Illinois. 

 1892. Chonetes mesoloba. Hall and Clarke, Pal. New York, vol. 8, pt. 1, pi. 16, fig. 22. 



Coal Measures: Illinois. 

 1894. Chonetes mesoloba. Keyes, Missouri Geol. Surv., vol. 5, p. 53. 



Upper Coal Measures: Kansas City, Mo. 



1899. Chonetes mesolobus. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 576. 

 Upper Coal Measures: Atoka quadrangle. 



1900. Chonetes mesolobus. Beede, Univ. Geol. Surv. Kansas, Rept., vol. 6, p. 71, pi. 9, figs. 3, 3b. 

 Lower Coal Measures: Fort Scott and Bronson, Bourbon County, Kans. 



The Colorado representatives of this well-characterized species are quite typical 

 in every way. It is not found at man}' localities, nor usually in great numbei-s, but 

 at station 2343, which is on Dolores River, in the Rico formation, it occurs in 

 abundance. Two different types of shell can be distinguished, one small in size and 

 with strong lobation, the other lai'ge, with the two sulci of the ventral valve 

 tending toward evanescence. Specimens from station 2238 in t^he San Juan region 

 represent the latter variety. I am disposed to advocate the distinction b}' a varietal 



