GEOLOGY OF THE FOURTH DISTRICT. 
ORGANIC REMAINS OF THE HAMILTON GROUP. 
No. 42. — No. 80, page 200. 
Fig. 1 and 1 a. Atrypa spinosa, H. Specimens from Eighteen-mile creek, with the spines 
removed. 
Fig. 1 b. A portion showing the imbricated lamellae and concentric elevated lines. 
Fig. 2. Atrypa spinosa, with the spines partially visible. Moscow. 
Fig. 3. Atrypa concinna, H. Moscow. 
Fig. 4. Strophomena inequistriata, Conrad (Jour. Acad. Nat. Sci. Vol. 8, p. 254, pi. 14, f. 
2). Moscow. 
Fig. 5. Delthyris zigzag, H. Moscow. 
Fig. 6. Calymene bufo, Green (Monograph, p. 41). Moscow. 
Fig. 7. Cryphceus calliteles , Green. Moscow. 
Fig. 8. Loxonema nexilis, Phillips (Palaeozoic fossils, p. 99, pi. 38, fig. 183. Terebra nex- 
ilis, Sowerby in Geol. Trans. 2nd series, Vol. 5, pi. 54, fig. 17). Seneca lake 
shore. 
No. 43. —No. 81, page 202. 
Fig. 1 . Avicula orbiculata, FI. Eighteen-mile creek. 
Fig. 2. Atrypa rostrata, H. Eighteen-mile creek. 
Figs. 3, 4 and 5. Undetermined species of Atrypa. Eighteen-mile creek. 
Fig. 6. Delthyris sculptilis, H. Eighteen-mile creek. 
No. 44. — No. 82, page 203. 
Figs. 1 and 2. Avicula decussata, H. 1. A cast in limestone. 2. The shell preserved in 
shale. 
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