242 CRETACEOUS LAMELLIBRANCHIA. 



Measurements : 



Length 

 Height 

 Tliickness . . 



(1. L* ) Lviujilie. 



Affinities. — This species is allied to T. rutinul't, J^ictet iuid Roux,' from the 

 Gaiilt of the Perte-du-Rhune and Sainte Croix, Ijut is distinguished by its more 

 rounded outline, smaller postero-dorsal area, and less distinct concentric ornament. 

 It is also allied to T. carinifern (p. 244). 



Bemarls. — Two internal casts of this species from Lympne are in the Museum 

 of Practical Geology (23470, 23471) ; the larger agrees closely with Sowerby's 

 figure, and may perhaps be the type, but the locality given by Sowerby is Court- 

 at-Street, 1^^ miles west of Lympne. A small, somewhat crushed example from 

 the Atherfield Clay at Dover colliery probably l)eIongs to this species. No other 

 specimens have been seen. The specimens recorded by Topley as 7'. riiriinfcrn 

 probably belong to T. rotiinJata. 



Disfriliiitioii. — Hythe Beds of Lympne and Court-at-8treet.- 



TuKAi'iA RoiiiNALDiXA r {(V Orhiijii i/), 1845. Plate XL, figs. 1 — 3. 



Descri2)tioii. — Shell oval, nearly equilateral ; I'ight valve more convex than 

 the left; posterior part not (juite so high as tlie anterior part ; postero-dorsal \)avt 

 compressed. Anterior margin rounded; ventral margin moderately convex; 

 posterior margin slightly curved ; postero-dorsal margin nearly straight. Umbones 

 rather prominent, curved posteriorly. Surface smooth, except for growth-lines. 



Measurements : 



Length 

 Height 

 Breadth 



(1) Penia-hed. (2, 3) Crackers, Atherfield. 



Remarls. — In the English specimens, which are here provisionally referred to- 

 T. h'iihlniikliiHi, the shell is jireserved, but the examples of that species figured l)y 

 d'()i'l)igny^ and by Pictet and Campiche' are internal casts, and it is consequently 



' ' Moll. Foss. Grcs verts de Greucve ' (1852), p. 414, pi. x.xix, fii,'. (3. Pictet and Campiche, ' Foss. 

 Terr. Cret. Ste. Croix' ('Mater. Pal. Suisse,' ser. 4, 1865), p. 117. 



- Thracia Nieoleti (Agassiz) has been recorded by Morris and by Topley Iroiu the Hythe Beds of 

 Hythe, but I have not seen any British examples of that species. 



3 ' Pal. Frau9. Terr. Crct.,' vol. ili (1845), p. 380, pi. ceclxxii, figs. 1, 2. 



■' 'Foss. Terr. Crct. Ste. Croix' ('Mater. Pal. Suisse,' ser. 4, 1865), p. 114, pi. cviii, figs. 5, 6. 



