43'2 CARRONIFEROUS FORMATIONS AND KAUNAS OF COLORADO. 



ences can be pointed out between my specimen and Heede's ligure, they hardly seem 

 to exceed such as might be reasonably ascribed to difference in age or to individual 

 peculiarity'. Certainly the expression of the two shells is very similar. On the 

 other hand, the relationship^ between M. polita and M. alata is so close, at least in so 

 far as it finds expression in external form, that I doubt whether the latter should be 

 considered more than a varietal aspect of White's species. 



Locality and horizon. — San Juan region (station 2312); Rico formation. 



AVICULOPINNA Meek, 1867. 



AvicuLOPiNNA ? PERACUTA Shumard. 



PI. IX, figs. 1, 2. 

 1858. Pinna penicula. Shumard, Acad. Sci. St. Louis, Trans., vol. 1, p. 214. 



Upper Coal Measures: Iowa Point, Nebraska; Kansas. 

 18(i0. Pinna adamsi. McChesney, Desc. New Spec. Pal. Foss., p. 7-t. 



Coal Measures: Lasalle, 111. 

 1872. Pinna peracuta. Meek, U. S. Geol. Surv. Nebraska, p. 198, pi. 6, figs. lla,b. 



Upper Coal Measures: Bennett's Mill, Wyoming; Nebraska City, Plattsmouth, Rock Bluff, and 

 ^ Bellevue, Nebr. 



Coal Measures: Iowa, Nebraska, Kansas, Missouri, and Illinois. 

 1875. Pinna peracuta (?). White, U. S. Geog.- Geol. Surv. W. 100th Mer., Rept., vol. 4, p. 151, pi. 

 11, fig. 5a. (Whole volume published in 1877.) 

 Carboniferous: Near Relief Spring, Ariz. 

 1884. Pinna peracuta. White, Geol. Surv. Indiana, 13th Kept., p. 145, pi. 28, figs. 1, 2. 



Upper, Middle, and Lower Coal Measures: Indiana. 

 1886. Pinna peracuta. Heilprin, Proc. and Coll. Wyoming Hist, and Geol. Soc, vol. 2, pt. 2, p. 272, 

 fig. 12; p. 273, fig. 12a. 

 Upper Coal'Measures: Mill Creek limestone, Wilkesbarre, Pa. 

 1886. Pinna peracuta. Heilprin, 2d Geol. Surv. Pennsylvania, Ann. Rept. for 1885, p. 455; p. 444, fig. 

 12; p.- 454, fig. 12a. 

 Upper Coal Measures: Mill Creek limestone, Wilkesbarre, Pa. 

 1892. Aviculopinna peracuta. Hyatt, Boston Soc. Nat. Hist., Proc, vol. 25, p. 388. 

 1895. Pinna peracuta. Keyes, Missouri Geol. Surv., vol. 5, p. 116, ■ pi. 45, figs. 2a, b (date of 

 imprint, 1894). 

 Upper Coal Measures: Kansas City, Mo. 



1899. Pinna peracuta. Girty, U. S. Geol. Surv., Nineteenth Ann. Rept., pt. 3, p. 579. 

 Upper Coal Measures: McAlester quadrangle; Atoka quadrangle. 



1900. Pinna peracuta. Beede, Univ. Geol. Surv. Kansas, Eept., vol. 6, p. 144, pi. 17, figs. 3, 3b. 

 Upper Coal Measures: Kansas City, Lawrence, Topeka, Kans. 



Meek described Aviculopinna in 1864," designating for its type Pinna prisca 

 ^ianstev = Avicula pinnceformis Geinitz.* He says of the genus (loc. cit. p. 212): 



"The typical species is an elongated, thin, nearh' or quite equivalve shell, with 

 the narrow tapering general form and very long hinge line of Pmna; from 



a Am. Joui. Sci., (2) , vol. 37, 1864, p. 212. '• Dyas, p. 77, pi. xlv, flgs. 1, 2, 3, and 4. 



