INTRODUCTION. 3 



Out of these 17 species 66 have been specifically described, while of the remain- 

 ing 11 the genus only could be determined. I admit this is rather a high percent- 

 age, but I think it much better to refrain from the specific determination of speci- 

 mens which are only known as fragments. I much deprecate the practice of many 

 modern authors who create new species, new genera, even new families, on frag- 

 ments which show so few distinguishing features, that uncertainty prevails as 

 to the main characters of species thus created. 



Out of the remaining 66 species 42 have been recognized as new, while 24 

 species could be identified with forms previously described. It is quite clear that 

 the chief interest rests with these 24 species, which are : — 



1. Orbitoliies macropora, Defrance. 



2. Orbitoides socialis, Leymerie. 



3. Ci/clolites regularis, Leymerie. 



4. Pyrina ataxensis, Cotteau. 



5. Hemipnemtes pyrenaicui, Hebert. 



6. Hemipaeusteg leymeriei, Hebert. 



7. Ostrea acutirostris, Nilsson. 



8. Ostrea pectinata, Lamarck. 



9. Ostrea ungulata, Sehlotheim. 



10. Gryphma vesicularis, Lamarck. 



1 1. Exogyra pyrenaica, Leymerie. 



] 2. Spondylus santoiiiensis, d'Orbigny. 



13. Tola quadncosta, Sowerby. 



14. Pecten dujardini, Kcemer. 



15. Cardita leaumonti, d'Arch. and Haime, var. balwhistanemis, Noetl. 



16. Cardita suhcomplanata, d'Arch. and Haime. 



17. Radiolites siihdilatata, MusehketofE. 



18. Corbttla harpa, d'Arch. and Haime. 



19. Trockus lartetianus, Leymerie. 



20. Neritapontica, d'Arcb. spec, 



21. Ovula expansa, d'Arch. and Haime. 



22. Volutiliihes latisepta, Stoliczka. 

 2-3. Nautilus suhlavigatus, d'Orbigny. 



24. Nautilus subfleuriausianns, d'Arch. and Haime. 



It will be convenient to exclude for a moment those species which are hitherto 

 only known to occur in Indian or Central Asian beds ; these are : — 



1. Cardita beanmonti, d'Arch. and Haime, var. baluchistanensis, Noetl. 



2. Cardita aubcomplanata, d'Arch. and Haime. 



3. Badiolites subdilatata, Muschketoff. 



4. Corbula harpa, d'Arch. and H»ime. 



5. Ovula expansa, d'Arch. and Haime. 



6. Volutilitkes latisepta, Stoliczka. 



7. Nautilus subfleuriausianus, d'Arch. and Haime. 



There remain, therefore, 17 species, or 26 per cent, of the total number, which 

 the Baluchistan upper cretaceous beds have in common with the cretaceous beds 

 of Europe ; and it is clear that it is these forms which we have chiefly to consider in 



B 2 



