of Eastern Pennsylvania. 213 



1 . Spirifera sculptilis Hall . . {</) 



2. /Spirifera fimbriate, (Con.) Hall* (a) 



3. Spirifera mucronata (Con.) Bill (c) 



4. Ort/ris Vavnxem i Ha 1 1 - (c) 



5. Nucleospira concinna Hall (c) 



6. Athyris spiriferoides (Eaton) Hall - ... (<■) 



7. Phacops rana. (.Green) Hall (c) 



8. Cypricardinia indenta (Con.) Hall (c) 



9. Atrypa reticularis (Linn.) Dal. . . . (c) 



in. (Jyrtina hamiltonensis Hal 1 _ . (?■) 



1 1. Tropidoleptus carinatus (Con.) Hall (rr) 



12. Chonetes coronata (Con.) Hall {rr) 



1 3. Strophodonta perplana (Con.) Hall (?) {rr) 



14. Leiorhynchus midticosta Hall (?) . . {rr) 



15. Actiiiopteria deciissata Hall (?) {r) 



16. Mytelarca {Plithomytihis) oviformis (Con.) Hall {rr) 



1 7. Conocardium sj> . . (rr) 



1 8. Platyceras pp. {rr) 



Corals and Bryozoa. 



This horizon is especially important since Professor White 

 considered it to be at the summit of the Hamilton stage 

 and to represent the Tally limestone of New York. After 

 describing the locality from which the above species were 

 collected, the Professor stated " There can be little doubt that 

 this stratum represents the Tully limestone horizon of the 

 New York Reports, and it thus becomes a valuable guide in 

 correlating and classifying the rocks of the district. "f How- 

 ever, when this zone is studied carefully it will be noticed that 

 it is usually a calcareous shale or sandstone, instead of a mas- 

 sive limestone and does not lithologically resemble the Tully 

 limestone of central New York. But, far more important 

 than the lithologic character of the zone, is the fact that the 

 fauna therein contained is composed of Hamilton species, 

 while those which, are especially characteristic of the Tully 

 limestone are absent.;}; This zone appears to. the writer to 

 correspond with the calcareous layers that occur in the midst 

 of the regular Hamilton shales of central New York rather 

 than with the Tully limestone. 



While considering the correlation of this zone it is impor- 



* Spirifer fimbria tus Morton was proposed in 1836, this Jour , vol. sxix, p. 150, 

 pi. II, fig. 1 ; while Conrad's Delthyris fimbriatus was named in 1842, Jour. Acad. 

 Nat. Sci., Philadelphia, vol viii. p. 26:-!. S. A. Miller in 1883, 2d ed. Am. Pal. 

 Foss. named Conrad's species Spirifera Conradana ; but in this paper the name 

 by which the New York species is generally known has been retained. 



fG 6 , p. 109. 



\ For a list of the New York Tully fauna with a discussion of the species 

 having a diagnostic value, see a paper by Prof. II. S. Williams on '■ The Cuboides 

 zone and its fauna; a discussion of methods of correlation." Bull. Geol. Soc. 

 Am., vol. i, pp. 490—194. 



