GEOLOGY OF THE FOURTH DISTRICT. 
ORGANIC REMAINS OF THE MARCELLUS SHALE. 
No. 39.— No. 71, page 180. 
Fig. 1. Orthoceras subulatum, H. Bloomfield, Ontario county. 
Fig. 2. Strophomena setigera, H. Avon, Livingston county. 
Fig. 3. Strophomena mucronata, H. Avon. 
Fig. 4. Strophomena pustulosa, H. Avon. 
Fig. 5. Avicula muricata, H. Avon. 
Fig. 6. Avicula Icevis, H. Avon. 
Fig. 7. Avicula equilatera, H. Bloomfield, Ontario county. 
Fig. 8. Ortliis nucleus, H. Avon. 
Fig. 9. Orbicula minuta, H. Avon. 
Fig. 10. Tentaculites jissurella, H. Avon. 
Fig. 11. Atrypa limitaris, Orthis limitaris, Vanuxem (Geol. Report). Le Roy, Genesee 
county. 
ORGANIC REMAINS OF THE HAMILTON GROUP. 
No. 40. —No. 78, page 196. 
Fig. 1. Belleroplion patulus, H. Kidder’s ferry, Cayuga lake. 
Fig. 2. Microdon hellastriata, Conrad (Jour. Acad. Nat. Sci. Yol. 8, p. 247, pi. 13, fig. 12). 
Fig. 3. Cucullea opima, H. Seneca lake shore. 
Fig. 4. Nuculal oblonga. Seneca lake shore. 
Fig. 5. Nucula lineatal Phillips (Palaeozoic fossils, p. 39, pi. 18, fig. 64). Cayuga lake 
shore. 
Fig. 6. Tellina? ovata, PI. Seneca lake shore. 
Fig. 7. Nucula bellatula, H. Ogden’s ferry, Cayuga lake. 
Fig. 8. Cypricardia truncata. {Cypricardites truncata, Conrad, Jour. Acad. Nat. Sci. Yol. 8, 
p. 244, pi. 12, fig. 17. See Geol. Yorkshire, pi. fig. ) 
Fig. 9. Modiola concentrica, H. (See Modiola semisulcata, Silurian researches, pi. 8, fig 6.) 
No. 41. —No. 79, page 198. 
Fig. 1. Turbo lineatus, H. Ovid, Seneca lake shore. 
Figs. 2 and 3. Delthyris mucronata, Conrad (Annual Report of New-York Geol. Survey, 
1841, p. 54). Eighteen-mile creek. 
Fig. 4. Atnypa prisca. (Terebratula affuns, M. C. t. . T. prisca, Yon Buch ; T. reti¬ 
cularis, Brown, Lethea Geognostica. Atrypa reticularis, Dalman. A. affinis, 
Silurian Researches.) Eighteen-mile creek. 
Fig. 5. Atrypa concentrica, Brown (Lethea Geog.) Eighteen-mile creek. 
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