A pp. A.] Dr. FiTTON on the Strata below the Chalk. 345 



which he himself had observed, might have escaped the notice of Desmarest's draughtsman ; nor 

 has he yet seen specimens from either of the localities given by that author. Besides the fossil 

 species of Cypris engraved in this plate, we are now acquainted with five others ; one in the 

 freshwater formation at Hordwell, (see Lyell in Geol. Trans, vol. iii. p. 288.) ; one in the coal of 

 Newcastle, {Cypris arcuata, Bean MSS.); and three found among tertiary marine shells of a 

 modern period, in the island of Java; — though the last possibly may belong to the Cytherina of 

 Miiller, a genus so near to Cypris, that it may not be distinguishable in the fossil state, and 

 the living species of which inhabit the sea. 



Fig. 2. Cypris tuberculata. Discovered by the Rev. G. E. Smith at Seabrook near Hythe. 

 Oblong-ovate, convex ; with a narrow border to the margin, and from three to twelve tubercles 

 upon the surface. The defined tubercles, and a distinct margin distinguish this species from 

 C. Faba ; it is also rather broader and flatter ; but the general form and the number of the tuber- 

 cles are variable, as well as the division across the middle of each valve, which in some speci- 

 mens, as at letter a., is so remarkable, as to indicate a distinct species, or even genus. More 

 perfect specimens, however, shown at h. and c. are quite free from this division ; and interme- 

 diate forms have been observed. The specimen represented in the upper figure at a. is from 

 Swanage Bay ; all the others are from the vicinity of Hythe. 



Fig, 3. Cypris spinigera. Discovered by Mr. Lonsdale in the Weald-clay of the Isle of 

 Wight. Oblong-ovate, broadest at one end, punctated ; furnished with a single, short, conical 

 spine on each valve ; by which, and a shorter form, it is distinguished from the other species. 

 It has a narrow lobe at one end of each valve of the same kind as in C.Faha. The specimens 

 a, are from Sandown Bay ; b. from Atherfield. 



Fig. 4. Cypris granulosa. Oblong-ovate, punctated ; with prominent granules upon its sur- 

 face ; the lobe at one end observable in C. Faba is wanting in this species. 



Fig. 5. Corbula alata. A rather gibbose, smooth shell, with the posterior side produced and 

 truncated. 



Fig. 6. Psammobial Tellinoides. (Psarwmoija, Mantell, Geol. S.E. of England, 251.) Shell 

 transversely oblong-ovate ; nearly flat, with conspicuous lines of growth. There are a few longi- 

 tudinal furrows upon the posterior side. 



Fig. 7. Cyclas parva. Rather thick, smooth, obovate, approaching lenticular; longer than 

 Cyclas media. The larger figure, under letter a., is magnified. The shell is found in great pro- 

 fusion in the Vale of Wardour. In the specimen represented at b., from Dallard's Farm, (supra, 

 p. 259, and also from pits at Dashlet,) the shells are filled with the crusts of a small smooth Cypris. 



Fig. 8. Cyclas subquadrata. Transversely oblong, with straight sides ; strongly marked with 

 lines of growth ; flat (perhaps from pressure). Found at St. Leonard's, Sussex. 



Fig. 9. Cyclas elongata. Transversely elongated, convex, nearly smooth ; posterior ex- 

 tremity more or less obliquely truncated : the casts of the outside show that the surface is finely 

 striated concentrically. There are two species of Cyclas in the specimen of slaty clay repre- 

 sented in the upper figure, a., which was found at Etchingham near Robertsbridge in Sussex. The 

 same forms occur also in the ferruginous sandstone of Langton Green, near Tunbridge Wells, 

 with Unio, (see below PI. XXI. fig. 16.); and in a bed of clay at the top of the cliffs on the west 

 of St. Leonard's. It is probable that the rounder species is Cyclas parva. Fig. 9. b. is a variety 

 of C. elongata, from HoUington near Hastings. 



Fig. 10. Cyclas media. (Min. Conch, t. 527. fig. 2.) A large specimen ; with another showing 

 the hinge and its single tooth under the beak. Transversely obovate, depressed, thick, smooth ; 

 anterior side small ; posterior rather pointed. 



2y 2 



