104 Mr. H. E. Strickland on the genus Cardinia. 



Mollusca, may be able to throw further light on the affinities of 

 these ambiguous yet characteristic fossils. 



Confining our attention therefore to the shells of the lias and 

 lower oolite, we will proceed to examine the species of Cardinia 

 which really exist in nature, as well as those which have been 

 described in books. 



I. Ascertained species of Cardinia. 

 1. Cardinia Listeri, Sow. (sp.) 

 Bonax ? Park. Org. Rem. pi. 13. f. 7. 

 Unio Listeri, Sow.Min. Con. pi. 154. f. 1, 3, 4. 

 Pachyodon Listeri, Stutchb. in Ann. Nat. Hist, vol.viii. pi. 9. f. 1, 2. 



Var. 1. Subelongate. 

 Cytherea latiplexa, Goldf. Petref. pi. 149. f. 6. 

 Unio hybrida, Sow. Min. Con. pi. 154. f. 2. 



Pachyodon hybridus, Stutchb. in Ann. Nat. Hist. vol. viii. pi. 9. 

 f. 3, 4. 



Cardinia hybrida, Agass. Et. Crit. Moil. pi. 12. 



Var. 2. Subcompressed. 

 Cytherea lamellosa, Goldf. Petref. pi. 149. f. 8. 



Var. 3. Lines of growth very numerous. 

 Pachyodon imbricatus, Stutchb. in Ann. Nat. Hist. vol. viii. pi. 9. 

 f. 5, 6. 



Var. 4. Small-sized (probably young). 

 Pachyodon cuneatus, Stutchb. in Ann. Nat. Hist. vol. viii. pi. 10. 

 f. 11,12. . 



Var. 5. 

 Cardinia amygdala, Ag. Et. Crit. Moll. pi. 12. f. 10—12. 



Formation : lower lias. 



Localities : Whitby, Yorkshire ; Grantham ; Langar, Nottingham- 

 shire ; Cropthorn, Defford and Eckmgton, Worcestershire ; Frethern, 

 Gloucestershire ; Wurtemburg. 



In Worcestershire and Gloucestershire this species is very abun- 

 dant in a zone of the lower lias, about 150 feet above the base of 

 that formation. Single valves are frequent. It is subject to much 

 variation in the thickness of the shell, the frequency and regula- 

 rity of the imbrications, and the length or shortness of the pos- 

 terior extremity. Having examined a very extensive series of 

 specimens, I have little doubt of the correctness of the above 

 synonyms. 



2. Cardinia crassissima, Sow. (sp.) 



Unio crassissima, Sow. Min. Col. pi. 153. 



Pachyodon crassissimus, Stutchb. in Ann. Nat. Hist. vol. viii. pi. 9. 

 f. 7. 



Lower oolite : Dundry ; Wick near Bath. 



Marlstonc : Dumbleton, Worcestershire. 



