Prosserand Cumings 



i — Lower Silurian Sections. 



689 



Very black, bituminous Utica slate forming the greater part 



Feet 



of the walls of the glen. It is quite calcareous and more fossilifCrous than 

 that in the exposures farther down the Mohawk valley, and the exposure of 

 fully 300 feet in the gorge belongs in the lower part of the Utica formation, 

 In the lower part of the gorge is a fall over Utica slate, the top of which is 

 about forty-five feet above the base of the slate. This locality was cited by 

 Mr. Darton as " one of the finest exposures [of Utica slate ] in the Mohaw k 

 valley," and a picture of the falls was given in his report.* 



The thin layers of Trenton limestone in the Canajoharie gorge are abun- 

 dantly fossiliferous and* the following species were collected : 



1. 



Rafinesquina altemata (Con.), Hall and Clarke. 



(o) 



2. 



Calymene catticephala, Green (?). 



0*) 



3. 



Orthis {Dalmanelld) testudinaria, Dal. 



(a) 



4. 



Asaphus platycephalus, Stokes. 





5. 



Monticulipora (Prasopord) lycoperdon, Say. 



(*) 



6. 



Modiolopsis mytiloides, Hall (?). 



(rr) 



7. 



Tellinomya levata, Hall. 



(rr) 



8. 



Zygospvra recurvirostra (Hall), Winch, and Schuch. 



(rr) 



9. 



Plectambonites sericea (Sowb.), H. and C. 



(c) 



10. 



Trimiclens corwenPricus, Eaton. 



(r) 



n. 



Atrypa {Protozyga) exigtta, Hall. 



(rr) 



12. 



Ceraurus pleurexantltem us, Green (?). 



(rr) 



13. 



Murchisonia bellicmcta, Hall. 



(rr) 



14. 



Murchisonia gracilis, Hall (?). 



(rr) 



15. 



Oamarella cf. Vblborthi, Bill. 



(rr) 



16. 



Stictopora sp. 



(r) 



As 



already stated, the Utica slate contains a larger number of fossils 



than has been found in the niore eastern exposures. The list is as follows, 



and it undoubtedly might be materially increased by further search. 



1. IAngula quadi^ata (Eich.), Hall (?). (c) 



2. Plectambonites sericea (Sowb.), H. and C. (a) 



3. Orthis (Dalmanella) testitdinaria, Dal. (c) 



4. Triarth/rus Bechi, Green. (c) 



5. Graptolites. (a) 



6. AsapTmsplatyeephalus, Stokes. (r) 



7. Tellinomya nuculifonnis. Hall. (r) 



* Ibid., p. 429, pi. 7. 



