232 CRETACEOUS T,A:yrETJJBRANCHIA. 



Tlie height of tlie anterior part of the sliell is less and the length of the ventral 

 margin greater relatively than in M. Sandse-CnirU (Pictet and Campiche).' 



Remarks. — This species varies somewliat in relative length and breadth, and 

 in the extent of the develo^Jment of the anterior furrow. Many of the specimens 

 are found in burrows in Avood. The protoplax is not preserved in any example seen. 



T//pe. — The type came from Speeton, but cannot now be found. 



DistrihuHon. — Speeton Clay of Speeton. Lower and Upper Gault of Folkestone. 

 Probably also in the Upper Greensand of Blackdown. Specimens wliifh 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 Claxb}- may lie due 

 to this species but the valves are concealed. 



Martesia ruiscA (Soirerhi/), 1828. Plate XXXVIII, fig. 11. 



]828. Pholas priscus, /. c!e C. Sowerhy. Miu. Couch., vol. vi, p. 157, ]il. dlxxxi. 



1845. Pholas ? priscus, E. Forbes. Quart. Jourii. Geol. Soc, vol. i, p. "237. 



1850. Pholas prisca, A. d'Orbigny. Prodr. de Pal., vol. ii, p. 72. 



1854. — — J.Morris. Cat. Brit. Foss., ed. 2, p. 221. 



1864. - — F. /. Pidet and G. Campiche. Foss. Terr. Crct. Ste. Croix 



(Matt'r. Pal. Suisse, ser. 4), p. 26. 

 1870. — — • (Martbsia), F. Stoliczha. Palaeout. ludica, Cret. Fauna 



S. ludia, vol. iii, p. 22. 

 1875. Pholadidea prisca, B. Etheridge iii W. Topley. Geol. Weald, p. 419. 



This species appears to be closely related to ill. constricfa, 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, and in 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 'Foss. Terr. Cret. Ste. Croix' (1864), p. 24, pi. c, tig. 1. This species has been recorded by 

 Price from the Gault of Folkestone ; I have not seen any examples of it. 



- Fistulana pijriformis, Mautell, is perhaps a Martesia, but no specimens showing the valves have 

 been seen. No figure or specific description was given by Mautell. The "type" came from 

 ■VVillingdon near Eastbourne, apparently from the top of the Lower Greensand. Mantell, ' Foss. S. 

 Downs' (1822), p. 76- Gastrochiena pyri/ormis, Morris, 'Cat. Brit. Foss.,' ed. 2 (1854), p. 203; 

 Pictet and Campiche, ' Foss. Terr. Crct. Ste. Croix (Mater. Pal. Suisse,' ser. 4, 1864), p. 18 ; Stoliczka, 

 'Palseont. ludica, Cret. Fauna S. India,' vol. iii (1870), p. 29. 



Gastrochwna dilatafa, Deshayes, has been recorded by Forbes and other writers from the Lower 

 Greeusand ; I have not seen an_y specimens in which the valves are exposed. Deshayes, in Leymerie, 

 ' Mem. Soc. geol. de France,' vol. v (1842), p. 2, pi. iii, fig. 1 ; Forbes, ' Quart. Jouru. Geol. Soc.,' vol. i 

 (1845), p. 237 ; Pictet and Campiche, ' Foss. Terr. Cret. Ste. Croix ' (1864) , p. 1 1 , pi. xcix. figs. 4. 5. 



