12 CRETACEOUS LAMELLIBRANCHIA. 



grooves, and also by the earlier part of the shell being nearly smooth. L. auber- 

 sonensis, Pictet and Campiche, 1 is relatively longer and has narrower grooves. 



Remarks. — On account of the imperfect figures of L. subrigida given by Romer, 

 the English specimens have not hitherto been referred to that species ; they agree 

 perfectly with the descriptions except in the number of ribs, but Dr. Wollemann 

 informs me that that character is variable. I have sent a specimen from the 

 Claxby Ironstone to Dr. Wollemann, and he is able to confirm my identification of 

 the species. Specimens from the Speeton Clay differ from those found in Lincoln- 

 shire in having fewer ribs with relatively fewer grooves, but since this is a very 

 variable character it cannot be regarded as indicative of more than a local variety. 



Fia. 3. — Lima (Plagiostoma) subrigida, Romer. Claxby Ironstone, Benniworth Haven. Area of right 

 valve, x J- Sedgwick Museum. 



Types. — From the Hilsthon of Brunswick. 



Distribution. — Claxby Ironstone (zone of Belemnites lateralis) of Benniworth 

 Haven. Upper part of the Speeton Clay of Speeton. 



Lima (Plagiostoma), sp. cf. Oubignyana, Mat heron, 1842. Plate III, figs. 10, a — e. 



1842. Lima Orbignyana, P. Matheron. Cat. Foss. des. Bouches-du-Rhone, p. 182, 



pf. xxix, figs. 3, 4. 



1846. A. d'Orbigny. Pal. Franc. Terr. Cret., vol. iii, p. 530, 



pi. ccccxv, figs. 1 — 4. 



1850. d'Orbigny. Prodr. de Pal., vol. ii, p. 107. 



1855. G. Cotteau. Moll. Foss. de l'Yorme, p. 100. 



1865. — H. Coquand. Mon. Aptien de l'Espagne, p. 149. 



1866. P. de Loriol. Foss. Oolitli. Corall. Valang. et Urgon. 



Mt. Saleve, p. 82, pi. D, fig. 13. 



1867. — de Loriol, in Favre. Rech. geol. Sans Savoie, vol. i, 



p. 387, pi. C, fig. 24. 

 1869. — — F. J. Pictet and G. Campiche. Foss. Terr. Cret. Ste. 



Croix (Mater. Pal. Suisse, ser. 5), 

 p. 126, pi. clxi, fig. 4. 

 1871. Radula (Acesta) Orbignyana, F. Stoliczlca. Palaiont. Iudica, Cret. Fauna 



S. India, vol. iii, p. 414. 



1 Loc. cit., p. 140, pi. clxiv, figs. 1, 2. 



