180 MOLLUSCA FROM THE CRAG. 



7. ASTARTE OMALII, Delajonkaire. Tab. XVII, fig. 1 af. 



ASTARTE OMALII. Lajonk. Not. Geol. env. d'Anv. (Mem. de la Soc. d'Hist. Nat. de Par.) 



torn, i, p. 129, pi. vi, fig. 1 a c, 1823. 

 Desk. Ency. Meth. Vers., t. xi, p. 77, No. 2, 1830. 

 Nyst. Rech., Coq. Foss. d'Anv., p. 7, No. 24, 1835. 

 Id. Coq. foss. de Belg., pi. 152, pi. ix, fig. 2 a, b, c, 1844. 



RUGATA. Lajonk (not J. Sowerby). Loc. cit., torn, i, p. 130, pi. 6, fig. 5 ac, 1823. 



Nyst. Rech. Coq. Foss. d'Anv., p. 7, No. 25, 1835. 



BIPARTITA. J. Sow. Min. Conch., t. 521, fig. 3, 1826. 



OBLONGA. J, Sow. Min. Conch., t. 521, fig. 4, 1826. 

 CRASSINA OMALII. Desk. 2dedit. Lam., t. vi, p. 258, 1835. 



BIPARTITA. Id. t. vi, p. 259, 1835. 

 ASTARTE. Lyell. Manual of Elem. Geol., 3d edit., p. 165, fig. 149, 1850. 



Spec. Char. Testa variabile, interdum oblongo-ovatd scepe trigonali ; subleevigatd 

 aut sulcatd, tumidd vel compressd, plurimum in&quilaterali, postice longiore, subangulatd ; 

 lunuld ovatd, prof nude excavatd ; natibus acutis, semper sulcatis : marginibus crenulatis. 



Shell variable, sometimes ovately oblong, often trigonal, smooth or sulcated, tumid 

 or compressed, for the most part inequilateral ; posterior side the longer, subangulated; 

 lunule ovate, deeply excavated ; umbones sharp, sulcated ; margin crenulated. 



Length, l-|ths of an inch; height, l^th ditto. 



Localities. Cor. Crag, Button, Ramsholt, Gedgrave. 

 Red Crag, Button. 



This shell is exceedingly abundant in all parts of the Coralline Crag. Of all the 

 species of this very variable genus found in the Crag, this is, ''par excellence" the most 

 perplexing and difficult to determine. There is a fossil found in the Middle and Upper 

 Tertiaries of America in which the variations in form appear even greater than in our 

 Crag shell, as shown by a large suite of specimens in the Cabinet of Sir Charles 

 Lyell, and that geologist, in his Paper upon the " Miocene Tertiary Strata of Maryland, 

 Virginia, and N. and S. Carolina," published in the ' Proceedings of the Geological 

 Society,' 1845, vol. iv, part iii, p. 555, considers A. vicina, A. arata, A. cuneiformis, 

 A. obruta, A.perplana, of the American authors, to be varieties of A. undulata, Say., in 

 which opinion I fully concur ; but he further says, " I have some specimens of 

 A. bipartita from the Suffolk Crag, which agree perfectly with the American fossil, 

 except that in the latter the sides of the hinge teeth are much more distinctly grooved. 

 A few only of the English specimens exhibit a faint trace of this grooving." In a 

 species so exceedingly variable as this appears to have been in the seas of the Coralline 

 Crag, and in the same, or at least in localities so little removed as those of Suffolk, 

 where they are now found, it is difficult to say what effect localities so far removed 

 as those of South Carolina might have produced upon an animal with such a tendency 

 to variation; there is scarcely a limit to be put to its specific range, and this ex- 

 cessively variable character is perhaps an argument in favour of specific identification. 



