GEOLOGY OF THE FOURTH DISTRICT. 
ORGANIC REMAINS OF THE NIAGARA GROUP. 
No. 15. — No. 38, page 108. 
Fig. 1 . Orbicula? squamceformis, H. Sweden, Monroe county. (Reference, Silurian Re¬ 
searches, p. 625, pi. 12, fig. 14 a.) 
Fig. 2. Lingula lamellata, H. Lockport. 
Fig. 3. Orbicula corrugata, H. Rochester. 
Fig. 4. Avicula emacerata, Conrad (Jour. Acad. Nat. Sci. vol. 8, p. 241, pi. 12, f. 15). 
No. 16. — No. 39, page 109. 
Figs. 1 and 2. Euomphalus hemisphericus, H. Rochester. 
Fig. 3. Cornulites arcuatus, Conrad (Jour. Acad. Nat. Sci. vol. 8, p. 276. pi. 17, f. 8). 
> 
No. 17. — No. 40, page 110. 
Fig. 1 . Orthoceras annulatum? (Reference O. annulatum, M. C. t. 133, Silurian Re¬ 
searches, pi 9, f. 5.) 
Fig. 2. Conulama quadrisulcata, Miller (M. C. t. 260, f. 3 and 4 ; His. Pet. Suec. p. 30, 
t. 10, f. 5 ; Silurian Researches, p. 626, pi. 12, f. 22). Lockport. 
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