106 EOCENE MOLLUSCA. 



This species appears to be restricted to the uppermost deposits ; I have not seen it 

 from below the Barton beds. It is not rare, though by no means so abundant as the 

 Paris Basin shell. On comparing the British fossil with the French species, the following 

 differences may be observed. Our shell is shorter, more elevated, and more regularly 

 ribbed in the direction of the lines of growth; the angle on the siphonal region is sharper 

 and more distinct, and there are only small, fine, and very faint rays upon the edge of the 

 pedal region, whereas in the French shell these rays are few, large, sharp, and very pro- 

 minent. The exterior of our shell has faint radiating lines, only perceptible in very perfect 

 specimens, and by the assistance of a magnifier; they are most distinct on the siphonal 

 region, particularly beyond the angular slope near the siphoni-lateral margin. The number 

 of denticles are fewer in our shell than in the French specimens. It may be called var, 

 delta-formis. ' 



2. Trigonoccelia cancellata, Deshayes. ' Tab. XIX, fig. 12. 



Trigonoccelta cancellata. Desk. An. sans Vert, du Bass, de Par., t. i, p. 838, pi. 64, 



figs. 31—^35, 1800. 



Spec. Char. T. " testa transversim trigond, injtatd, subaqiiilaterali, antice obtusd,postice 

 acute angulatd, striis longitudinalibus, transversalibusqice, eleganter decussatd, ad latus anti- 

 c-inn longitudinalibus, proeminentioribus, distantioribus ; latere postico piano, ovato, angulo, 

 acuto, aliquantisper proeminenti separato, liris tenuibus distantibus ornato ; cardine brevi, 

 angusto, paucidentato ; dentibus minimis, sapius complicatis, fossuld ligamenti satis lata, 

 regulariter triangularis — Desh. 



Shell elongately trigonular, slightly inflated ; subequilateral j pedal region the larger, 

 somewhat inflated ; pedilateral margin rounded ; siphonal region slightly compressed, 

 angular, with pointed termination ; exterior radiated and decussated by prominent and 

 regular lines of growth ; hinge-area small, denticles few ; depression for connexus broadly 

 triangular and shallow. 



Length, \ an inch. 



Localities. Huntingbridge. 



France: Parnes, Damery-Auvers, Acy, Mary, Caumont, Crouy, La Ferte- 

 sous-Jouare, Le Fay el {Deshayes). 



A single specimen only of this species has been obtained by Mr.. Edwards, and that 

 unfortunately is not quite perfect ; a part of the hinge-area has been destroyed, but the 

 exterior and general contour of the shell correspond with the French species, and it may 

 fairly remain with the above name for the present. It is quite distinct from our delto'idea. 



