70 CRETACEOUS LAMELLIBRANCHTA. 



Affinities. — The shell in this species is larger, relatively higher, more oblique, 

 and less inflated than in .1. Keijserlingiana (see below). The right valve is more 

 flattened, and its umbo is only slightly curved. The umbo of the left valve is 

 larger and more prominent. 



BemarJcs. — The only specimens I have seen are internal casts from the Spilsb}' 

 Sandstone. The example of this species described by Pavlow as var. raiHolata 

 shows faint radial ribs on the internal cast of the right valve, and a slight 

 depression on the left valve extending from the umbo to the postero-ventral 

 margin (Plate X, fig. 2). 



Types. — From the Upper Volga beds of Kaschpur (Simbirsk), Staraja-Rjasan, 

 and Olenek. The specimens figured l)y Pavlow are in the Sedgwick Museum and 

 are here re-figured. 



Bislriliitiov. — Spilsby Sandstone (zone of Belemnites lateralis) of Donnington. 



AucELLA KETSEELmGiANA, TrautschoU, 1868. Plate X, figs, oa — d, 'ia,h, 5. 



1837. In.oceeamus concentricus, G. Fischer de Waldhetni. Orvctographie clu 



gouvernm. de Moscou, p. 177, 

 pi. XX, figs. 1 — 3. 

 1846. AxjCELLA CONCENTRICA, vcir. EUGOSA, A. Kei/gerlimj. Eeise in das Petscbora- 



Laud, p. 300, pi. xvi, fig. 16. 

 18.50. AvicuLA (Buchia) n. sp., F. Homer. Neues Jalirl). fiir Miu., etc., p. 393. 

 1868. AucELLA Keyseelingiana, H. TrautschoJd . Verluiudl. d. russisch-kaiser- 



licli. iiiiueral. Gresellscli. in Peters- 

 Imrg, ser. 2, vol. iii, p. 250. 

 1874. — CONCENTRICA, var. EUGOSA, F. Totila. Mesozoisch. Yerstein. v. d. 



Kiihu-Iusel (Die zweite deutsch. 

 Nordpolf., in 1869, 1870, iinter 

 Kapitiin K. Koklcwev), vol. ii, 

 p. .503, pi. ii, figs. 2, 3. 



1874. — — var. rugosissima, F. Tmila. Ihid., p. 504, pi. ii, 



fig. 4, 



1875. Perna imbricatus [Beau MS.], J. PhUUpg, Geol. York?;., pt. i, ed. 3, p. 247. 

 — — VEN0STULUS [Bean MS.], Phillips. Ibid., p. 247. 



1884. AvicuLA? teutoburgiensis, 0. Weerth. Neocoui. im TeiitoKurg. Walde 



(Palajout. Abhaudl., vol. ii), 

 p. 50, pi. ix, fig. 9. 



1886. AucELLA Keyseelingiana, /. Lahuseii. Mem. Acad. Imp. St. Pt'tersbourg, 



ser. vii, vol. xxxiii, No. 7, p. 4. 



1888. — Keyserlingi, J. Lahusen. Ueber die riissischeu Aucelleu (Mt'm. 



Comite geol. Euss., vol. viii. No. 1), 

 pp. 21, 40, pi. iv, figs. 18—23. 



1889. Inoceeamus venustulus et imbricatus, G. W. Lamj'luyh. Quart. Journ. 



Geol. Soc, vol. xlv, p. 615. 



