232 CRETACEOUS LAMELLIBRANCHIA. 
The height of the anterior part of the shell is less and the length of the ventral 
margin greater relatively than in M. Sancte-Crucis (Pictet and Campiche).' 
Remarks.—This species varies somewhat in relative length and breadth, and 
in the extent of the development of the anterior furrow. Many of the specimens 
are found in burrows in wood. The protoplax is not preserved in any example seen. 
Type. 
The type came from Speeton, but cannot now be found. 
Distribution.—Speeton Clay of Speeton. Lower and Upper Gault of Folkestone. 
Probably also in the Upper Greensand of Blackdown. Specimens which belong to 
either this or a closely allied species occur in the Spilsby Sandstone of Benniworth 
Haven. Borings in wood found in the Tealby Limestone of Claxby may be due 
to this species but the valves are concealed. 
Marresta prisca (Sowerby), 1828. Plate XXXVIII, fig. 11. 
1828. Puouas priscus, J. de C. Sowerby. Min. Conch., vol. vi, p. 157, pl. dlxxxi. 
1845. PHouas? priscus, H. Forbes. Quart. Journ. Geol. Soc., vol. i, p. 237. 
1850. Puonas prisca, A. d’Orbigny. Prodr. de Pal., vol. 11, p. 72. 
1854. — — J. Morris. Cat. Brit. Foss., ed. 2, p. 221. 
1864. — — F.J. Pictet and G. Campiche. Foss. Terr. Crét. Ste. Croix 
(Matér. Pal. Suisse, ser. 4), p. 26. 
1870. — — (Marrzsia), F. Stoliczka. Paleeont. Indica, Cret. Fauna 
8. India, vol. i, p. 22. 
1875. PuHonaprpEa Prisca, R. Etheridge in W. Topley. Geol. Weald, p. 419. 
This species appears to be closely related to M. coustricta, but no satisfactory 
description can be given until better specimens have been obtained. The type, in 
which the shell was well preserved, cannot now be traced ; in other examples the 
shell is concealed by a coating of hard matrix, andin the few cases in which it has 
been possible to remove the matrix only internal casts of the valves have been 
exposed. The type came from the Lower Greensand (? Sandgate Beds) near 
Sandgate. Other specimens have been obtained from the Hythe Beds of Hythe 
and Maidstone.’ 
1 «Boss. Terr. Crét. Ste. Croix’ (1864), p. 24, pl. c, fig. 1. This species has been recorded by 
Price from the Gault of Folkestone; I have not seen any examples of it. 
2 Fistulana pyriformis, Mantell, is perhaps a Martesia, but no specimens showing the valves have 
been seen. No figure or specific description was given by Mantell. The “type” came from 
Willingdon near Eastbourne, apparently from the top of the Lower Greensand. Mantell, ‘ Foss. 8. 
Downs’ (1822), p. 76; Gastrochena pyriformis, Morris, ‘Cat. Brit. Foss.,’ ed. 2 (1854), p. 203; 
Pictet and Campiche, ‘ Foss. Terr. Crét. Ste. Croix (Matér. Pal. Suisse,’ ser. 4, 1864), p. 18 ; Stoliczka, 
‘Paleont. Indica, Cret. Fauna S. India,’ vol. iii (1870), p. 29. 
Gastrochena dilatata, Deshayes, has been recorded by Forbes and other writers from the Lower 
Greensand; I have not seen any specimens in which the valves are exposed. Deshayes, in Leymerie, 
‘Mém. Soe. géol. de France,’ vol. v (1842), p. 2, pl. iii, fig. 1; Forbes, ‘ Quart. Journ. Geol. Soc.,’ vol. i 
(1845), p. 237; Pictet and Campiche, ‘ Foss. Terr. Crét. Ste. Croix’ (1864), p. 11, pl. xcix, figs. 4, 5. 
