OBOLIDJi;. 545 



The visceral area of Oholus sinoe (PI. XXVI, fig. 2ej is somewhat Hke that of Lingulella 

 (Lingulepis) acuminata (PI. XLII, fig. Ig), and also resembles the visceral area of the ventral 

 valve illustrated by Hall [1863, PI. VI, fig. 15]. The condition of preservation and the original 

 impress made by the different parts of the animal on the shell varies so much in shells of the 

 same species that it is difncult, without a large series of specimens, to decide definitely upon 

 generic or specific characters in the Obolidse. Tliis is particularly true of Oholus, Lingulella, 

 and Lingulepis. 



Of the 14 species and 2 varieties referred to Lingulepis from the Cambrian, 1 species 

 occurs in the Lower Cambrian, 9 species and 2 varieties in the IVIiddle Cambrian, and 5 in 

 the Upper Cambrian. One species, L. (L.) acuminata (Conrad), is common to the Middle and 

 Upper Cambrian and Ordovician. 



For the species that have been referred to Lingulepis and which are now referred to other 

 genera, see pages 62-63. 



^ Lingulella (Lingulepis) acuminata (Conrad)." 



\ 



Plate XXXIV, figures 3, 3a-e; Plate XL.^ftgures 1, la-s; Plate XLI, figures 1, la-n; Plate XLII, figures 1, la-o. 



Lingula acuminata Conrad, 1839, Third Ann. Kept. New York State Survey, p. 64. (Described as a new species.) 

 Lingula antiqua Emmons, 1842, Nat. Hist. New York, Geology, pt. 2, p. 268, fig. 68. (Occurrence discussed. Fig. 68 



is copied in this monograph, PI. XL, fig. la.) 

 Lingula antiqua Emmons, Hall, 1847, Nat. Hist. New York, Paleontology, vol. 1, pp. 3-4, PL I, figs. 3a-e. (Described 



and discussed as a new species, but uses Emmons's name.) 

 Lingula acuminata Conrad, Hall, 1847, idem, p. 9, figure with footnote. (Copies the original description of Conrad, 



1839, p. 64. The figure is copied in this monograph, PL XL, fig. 1.) 

 Lingula prima Owen, 1851, Proc. Am. Assoc. Adv. Sci. for 1851, p. 170. (Mentioned.) 

 Lingula antiqua Emmons, Owen, 1851, idem, p. 170. (Mentioned.) 



Lingula antiquata Emmons, 1855, American Geology, vol. 1, pt. 2, pp. 202-203, PL IV, fig. 7. (Described and dis- 

 cussed. Fig. 7 is copied from Emmons, 1842, fig. 68, p. 268.) 

 Lingula acuminata Conrad, Emmons, 1855, idem, p. 203, PL IV, fig. 9. (Described. Pig. 9 is copied from Hall, 1847, 



p. 9, footnote.) 

 Lingula prima Owen, Billings, 1856, Canadian Naturalist, 1st ser., vol. 1, p. 34, fig. 1. (Described.) 

 Lingula antiqua Emmons, Billings, 1856, idem, p. 34, fig. 2. (Characterized.) 



Lingula acuminata Conrad, Billings, 1863, Fifteenth Rept. Geol. Survey Canada, p. 102, figs. 8a-g. (Mentioned.) 

 Lingula acuminata Conrad, Chapman, 1863, Canadian Jour. Ind., Sci. and Art, new ser., vol. 8, p. 187, fig, 155. (Men- 

 tioned.) 

 Lingula antiqua Emmons, 1863, Manual of Geology, 2d ed., p. 92, fig. 77. (Mentioned. Fig. 77 is copied from Emmons, 



1842, fig. 68, p. 268.) 

 Lingula acuminata Conrad, Chapman, 1864, Minerals and Geology of Canada, p. 159, fig. 155. (Text and figure copied 



from Chapman, 1863, p. 187, fig. 155.) 

 Lingulepis minima Whitfield, 1884, Bull. Am. Mus. Nat. Hist., vol. 1, No. 5, p. 141, PL XIV, figs. 1 and 2. (Described 



and discussed as a new species.) 

 Lingulepis minima 'WTiitfield, Dwight, 1886, Proc. Am. Assoc. Adv. Sci. for 1885, p. 208. (Mentioned.) 

 Lingulepis acuminata Conrad, Dwight, 1886, idem, p. 208. (Mentioned.) 

 Lingula antiqua Emmons, James, 1895, Am. Naturalist, vol. 29, p. 884, fig. 1. (Mentioned. Fig. 1 is copied from 



Emmons, 1842, fig. 68, p. 268.) 

 Lingulepis acuminata (Conrad), Matthew, 1895, Trans. Roy. Soc. Canada for 1894, 2d ser., vol. 1, sec. 4, No, 13, 



pp. 257-258, PL II, figs. 5a-b. (Described and discussed.) 

 Lingulepis acuminata (Conrad), Schuchert, 1897, Bull. U. S. Geol. Survey No. 87, p. 259. (Discussed.) 

 imgrufepis acumtnato (Conrad), Walcott, 1897, Am. Jour. Sci., 4th ser., vol. 3, p. 404. (Merely changes generic 



and specific references.) 

 Oholus {Lingulepis) acuminatus (Conrad), Walcott, 1899, Mon. U. S. Geol. Survey, vol. 32, pt. 2, p. 443. (Merely 



changes generic and specific references.) 



Synonymy of the forms that have been referred to Lingulepis pinnaformis (Owen) from 

 the Mississippi Valley, and which are now referred to Lingulella (Lingulepis) acuminata (Conrad) : 



Lingula prima Owen, Hall, 1851, Rept. Geology Lake Superior Land District, by Foster and Whitney, pt. 2, p. 

 204, PL XXIII, figs. la-g. (Described and discussed; dorsal valves.) 



o The synonymy for this species is given in two parts; first, the synonymy of the forms that have been referred to the species acuminata; 

 second, the .synonymy of the forms that have been referred to the species pinnaformis. The latter species is now considered to be a synonym of 

 the former. 



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