DERIVED FOSSILS. 151 



N. Europe. Schoppenstedt, Hils conglomerat. 

 S. Europe. Switzerland, Valengien to Urgonien ; Paris area, 

 Neocoinian. 



THETIS MINOR, Sby. 



Thetis minor, Sby. Characteristic specimens occur not unfre- 

 quently in the Upware grit boulders, associated with Trigonia 

 ornata, Litorina, sp. Pecten orbicularis, and a small sub-triangular 

 bivalve. 



It is more common at Potton. 



Localities. Shanklin; Wiltshire (Morris); Speeton (Upper 

 Neocomian). 



TRIGONIA ORNATA, d'Orb. (Lycett). 

 Trigonia ornata, d'Orbigny Lycett. Brit. Foss. Trigonia, Pal. 



Soc., p. 139, pi. xxiv., figs. 6, 7. 

 Localities. Hythe ; Atherfield, in the Perna bed. 

 S. Europe. Perte du Rhone, Aptien ; Paris area. 



TRIGONIA SPINOSA, Park. ? 



Trigonia spinosa, Park. ? Lycett, Brit. Foss. Trigonia, Pal. Soc. 

 p. 136, pi. XXIIL, f. 10; pi. xxiv., figs. 8, 9. 

 Localities. Brickhill ; Blackdown beds ; Isle of Wight (Upper 

 Greensand). 



CUCULL^EA VAGANS 1 , Sp. nov. 



(Plate viii., fig. 8, a, b.) 



Shell globose, nearly equilateral, ornamented with strong, 

 radiating ribs. Umbones prominent, rounded, slightly anterior. 

 Hinge line straight; teeth few, oblique in the cardinal region, 

 longitudinal at the sides ; the lateral ones are striated across. 

 Area triangular, moderate, with angular cartilage grooves. 



Ribs about 25 in number, strong and equal over the back, 

 faint in the cardino-lateral region ; they are well defined, angular 

 in cross section at the sides, but more rounded over the back. 

 Secondary striae usually run along upon the ribs. Interspaces 

 broader than the ribs, widest at the sides, often with faint radiating 



1 Vagari, to wander. It occurs in scattered blocks, being unknown in situ. 



