of the Thradan Bosphorus. 387 



a dark grey colour, and slightly crystalline. It is exposed in extensive quar- 

 ries, where it is traversed by some remarkable trap-dikes, to be mentioned 

 hereafter. Organic remains are rare in the limestone ; but I detected a few 

 impressions of Terebratulae and crinoidal stems, exhibiting the same crystal- 

 line fracture, which distinguishes them in the carboniferous and other lime- 

 stones of England. 



Above the limestone is an argillaceous schist, with an oblique cleavage, and 

 it extends to the summit of the hill. Impressions of shells, similar to those of 

 Arnaout-keui, occur in it in many places, and in tolerable abundance. I 

 have found only one specimen, which can be referred to the family of Trilo- 

 bites. It is a small fragment, but it so accurately exhibits the structure of the 

 eye of an Asaphus, that I have no hesitation in referring it to that genus. 



The following is a list of the fossils of this formation, as far as the imper- 

 fection of the specimens admits of identification. I am indebted to Mr. 

 Murchison and Mr. James De Carl Sowerby for assistance in determining 

 these fossils. 



Brachiopoda. 



1. Spirifer. — Allied to Spirifcr specioms, Bronn. Leth. Geog. II. 15. 



2. Spirifer. — 'An undetermined species. 



3. Producta (Leptoena) sericea ? 



4. Producta {Leptoena) euglypha ? Dalm. 



5. Producta (Leptoena). — New species. 



C. Terebratula affinis, Min. Con. — In the Upper Silurian series of Great Britain. 



7. Terebratula unguis ? — In the Caradoc sandstone of Great Britain. 



8. Atrypa. — An undetermined species. 



9. Orthis. — New species. 



10. Orthis. — New species. 



Crustacea. 



11. Asaphus. — Eye like that in Buckland's Bridgewater Treatise, pi. XLV. fig. 10'. 



Crinoidea. 



12. Detached joints of undetermined genera. 



Polyparia. 



13. Ctjathophyllum, Goldf. 



14. Favosites, Lam. — Similar to one in the Cambrian rocks. 



Should any geologist ever devote that share of time and attention to this 

 country, which it well deserves, he would probably find several other localities 



VOL. V. SECOND SERIES. 3 E . 



