114 CRETACEOUS LAMELLIBRANCHIA. 



? I860. AsTiRTE OBOVATA, H. Coqiiand. Mou. Aptieu de rEspague, p. I'l'l. 



pi. xiii, figs. 3, 4. 

 1866. — — F. J. Pidct and G. Campiclie. Foss. Terr. Crct. Ste. 



Croix (Mater. Pal. Suisse, sur. 4), p. 312. 

 1871. — — (Ebyphyla), 2*'. /S<oZic«A;a. PaliBont.Indica.Cret.Fauua. 



S. ludia, vol. iii, p. *285. 

 1892. — — 0. Buhrciidscn. Zeitscbr. d. deutsch. geol. Gesellsch., 



vol. xliv, p. 22. 



Description. — Shell large, oval, transverse, moderately inflated, very ineciui- 

 latcral. Anterior margin rounded, concave in front of the nmbo. Behind the 

 umbo the dor.sal margin has a gentle and regular curve. Posterior margin roumled 

 or sub -truncate. ITmbones prominent, curving forward. Lunule deep. Escutcheon 

 narrow, deep. 



Ornamentation consists of numerous, strong, close, somewhat irregular concent i-ic 

 ribs, on which fine, concentric, linear ribs occur. 



Measurements : 



(1) (2) (3) (1) (0) (6) 



Length . . 75 . 74 . 73 . 70 . 72 . 71 mm. 

 Height . . 62 . 58 . CO . 59 . 63 . 59 „ 



(1-4) Per«n-bed, Atlierfield. 

 (5, 6) Per»a-bed, Sandown. 



Affinities. — Astarte Beaumonti, Leymerie,' and A. transversa, Leymerie,- are 

 closely allied to A. ohovata, and were regarded by Forbes as merely varieties of the 

 latter. Pictet and Renevier (1857) were inclined to regard the differences as not 

 of specific importance. Pictet and Campiche (1866), however, kept the three forms 

 distinct, but wei^e uncertain whether they should be regarded as species or varieties. 

 They state that in A. Beaumontl the margin is smooth, Avhilst in A. obooata and 

 A. transversa it is crenulated. In the first two forms the posterior margin i.s nioi-e 

 rounded, Ijut in the last it is more truncate. It is very doubtful whether the 

 crenulation of the margin is a feature of specific importance in Astarte; indeed, 

 one writer^ thinks that it is a characteristic of sex. Whether the other differences 

 are of specific value can be determined only by the comparison of a number of 

 examples of A. Beaumunti and A. transversa with specimens of A. ohovata. 



1 ' Mem. Soc. geol. de France,' vol. v (1842), pp. 4, 24, pi. iv. fig. 1. D'Orbigny, 'Terr. Cret.,' 

 vol. iii (1844), p. 60, pi. eclx. Pictet and Campiche, 'Terr. Cre't. Ste. Croix' (1866), p. 300, pi. cxxiv, 

 fig. 1. WoUemaun, ' Biv. u. Gastrop. d. deutsch «. hoUiiud. Neocoms ' (1900), p. 95. 



'■^ Op. cit. (1842), pp. 4, 24, pi. v, fig. 5 D'Orbigny, "p. cit., p. 61, pi. cclxi. Pictet and C.impiche, 

 op. cit., p. 301, pi. exxiv, fig. 2. De Loriol, ' Auim. Invert. Foss. Mt. Salcve ' (1861), p. 68, 

 pi. viii, fig. 9. 



■' A. Ostrooumoff, 'Zool. Anzeiger,' vol. xxiii (1900), p. 499. 



