172 PERMIAN FOSSILS. 



Byssoarca striata, ScJdotheim. Plate XV, figs. 7, 8, 9. 



Mytilites stkiatus, Schl. Miincli. Akad., vol. vi, p. 31, pi. vi, fig. 3 a, b, c, 1816. 



— — „ Petrefactenkunde, p. 298, 1820. 



— — „ Boue, Edin. Phil. Journal, vol. xii, p. 144, 1825. 

 CucULL^A, N. S., Phillips. Phil. Mag., vol. iv, p. 401, 1828. 



— SULCATA, J. de C. Sow. Trans. Geol. Soc. Lond., 2d series, vol. iii, p. 119, 



1829. 



— — „ De la Beche, Geol. Man., p. 384, 1831; Germ. 



Transl,, p. 4.59, 1832 ; 3d Eng. ed., p. 573, 1833. 

 Mytilus steiattjs, Schl. Op. cit., Germ. Transl,, p. 459, 1832; 3d Eng. ed., p. 573, 



1833. 

 — — „ Phillips, Encyc. Mel., vol. iv, p. 610, 1834. 



CucuLL^EA SULCATA, J. de C. Sow. Loc. cit. 



— — „ Thomson, Outlines of Geology, &c., vol. ii, p. 314, 



1836. 

 Arca ANTiauA, Miinster. Goldfuss, Petrefacta, 2d part, p. 145, pi. 122, fig. 8. 

 CucuLL^A SULCATA, /. de C. Sow. Morris, Catalogue, p. 85, 1843. 

 Arca antiqua, Miinster. Geinitz, Gsea von Saehsen, p. 95, 1843. 



— — ,, De Verneuil, Bull. Soc. Geol. de France, 2™' serie, vol. i, p. 32, 



1844. 



— — ,, Geol. Russ., vol. i, p. 224, 1845. 



Byssoarca tumida, J. de C. Sow. (partim). King, Catalogue, p. 11, 1848. 

 Akca Loftusiana, Hawse. Trans. T. N. F, C, vol. i, pp. 246, 247, 1848. 

 (?) — tumida, J. de C. Sow. Geinitz, Versteinerungen, p. 9, pi. iv, fig. 7, 1849. 



Diagnosis. — " Shell ovato-trapezoidal, ventricose, the umbones intermedial! and 

 distant, the underside sub-compressedly declining, marked with numerous radiating, 

 closely-set, furcated, granulated lines."^ (MiJnster.) 



This species, which has been variously named by Schlotheira, J. de C. Sowerby, 

 and Miinster, was considered in my ' Catalogue' as a variety of Byssoarca tumida, — the 

 fossil next to be considered. It is certainly the CucuUcsa sidcata of J. de C. Sowerby ; 

 as I have seen a specimen thus named in the collection of this gentleman. 



Those who contend for its distinctiveness, compared with Byssoarca tumida, may 

 dwell on its greater width, more approximate umbones, and less rounded ventral 

 margins ; it cannot be denied, however, that specimens occur apparently militating 

 against their being specifically separated. 



The specimen represented by Count Miinster, in the ' Petrefacta,' has the ribs slender, 

 divided toward the ventral margins, and finely granulated or nodulous ; but specimens 

 occurring at Humbleton and Tunstall Hills have generally the ribs simple, somewhat 

 stronger, and rather more coarsely nodulous. 



This species has only anterior and posterior teeth, which are nearly parallel to the 



1 "Area testa ovato-trapezoidea-ventricosa, umbonibus antemedianis et distantibiis, latere postico sub- 

 compresso-declivi, lineis radiautibus crcbris confertis furcatus granulatis." (Goldfuss's Petrefacta, 2d part, 

 p. 145. 



