GEOLOGY OF THE FOURTH DISTRICT. 



ORGANIC REMAINS OF THE NIAGARA GROUP. 



No. 15. — No. 38, page 108. 

 Fig. 1. Orbicula? squamafo-nnis, II. Sweden, Monroe county. (Reference, Silurian Re- 

 searches, p. 625, pi. 12, fig. 14 a.) 

 Fig. 2. Lingula lamella ta, H. Lock port. 

 Fig. 3. Orbicula corrugata, H. Rochester. 

 Fig. 4. Avicula emacerata, Conrad (Jour. Acad. Nat. Sci. vol. 8, p. 241, pi. 12, f. 15). 



No. 1C — No. 39, page 109. 

 Figs. 1 and 2. Euomphalus hemisphericus, II. Rochester. 

 Fig. 3. Cornulites arcuatus, Conrad (Jour. Acad. Nat. Sci. vol. 8, p. 27G. pi. 17, f. 8). 



No. 17. — No. 40, page 110. 



Fig. 1. Orthoceras annul atum? (Reference O. annul atum, M. C. t. 133, Silurian Re- 

 searches, pi. 9, f. 5.) 



Fig. 2. Conulana quadrisulcata, Miller (M. C. t. 260, f. 3 and 4 ; His. Fet. Suec. p. 30, 

 t. 10, f. 5 ; Silurian Researches, p. 626, pi. 12, f. 22). Lockport. 



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