SYNOPSIS OF GENERA. Ux 



1875. Geological Survey of Ohio, vol. 2, pi. 11; PaljBontology, 292, Mr. 

 Meek describes Entolium Shumardianwn, WmcheWl (sp.), pi. 15, figs. Aa, b = 

 Pernopeden Shumardianus, Winchell (1865). Proc. Acad. Nat. Sci. Philad., 

 xvii, 126. 



Compare P. limatus, Winchell (1865), ib., and Avicula Cooperensis (1855), Mis- 

 souri Geol. Rep. 



1877. Mr. S. A. Miller, Catalogue of American Palaeozoic Fossils, cites Ento- 

 lium avicula, Swallow, 1858 {Peden aviculus), Trans. St. Louis Acad. Sci., Coal 

 Measures, and E. Cooperensis, Shumard, 1855 {Avicula Cooperensis), Low. Carb. 



1865. Professor A. Winchell describes the genus Pernopecten (Proc. Acad. 

 Nat. Sci. Phila., 1865,* p. 125. 



The author founds the genus upon Aviculopeden limiformis. White and Whit- 

 field, from the Burlington sandstone of Iowa. Professor Winchell also includes 

 under this genus, Pernopecten limatus, and a new species from the base of the 

 Burlington limestone, together with Pernopecten Shumardianus, Winchell, which 

 he says is Avicula circulus. Hall (not of Shumard) with Lima ? nbsoleta. Hall, 

 Lima glaber, H., and mentions several European species. " It agrees with 

 " Amussium in its sub-symmetrical ears, central cartilage-pit, and the absence of 

 " radiating ridges, but differs in its straight hinge-line and lateral cartilage-pits. 



" It is probable that in addition to the two following species, others referred 

 " to Avicula, Peterinea and more especially Aviculopeden, Amussium and Peden, 

 " will be found to possess the assemblage of characters shown in Pernopecten. 

 "Lima? obsoleta. Hall (Rep. 4th [10th in error] Dist. N. Y., p. 265) = Pecten 

 " sub-obsoletus, D'Orb., is stated to have a ' crenulated hinge-line,' while its 

 " external characters are quite conformable to Pernopecten. Not improbably 

 " Lima glaber. Hall, belongs to the same association. The same may be said of 

 " Peden densistria, Sandb., from the Posidonomt/enschiefer of Nassau ; Avicula 

 " tumida and Avicula lavigata, de Koninck, from the Carboniferous limestone of 

 " Belgium, etc., etc." [Proceedings Acad. Nat. Sci., Phila., July, 1865, pp. 

 125, 126.] 



♦This publication bears the imiii'int of July, 186.'). The Geo\og\ca,\ Report of California, containing the 

 ori^nal description of Eutoliuiu, bears date of 1865, and the Preface is dated November, 1865. 



