CORRELATION OF STRATA. CX1x 
Hudson or| 
Trenton Period. [eases 
Stones Black Trenton 
Gaver || Givee || Grow. 
j as] « : I 
GASTROPODA. melee 3 g\s 3 2 Sy 2 a = 
aq/2)/a/2/4| af 8 \sele]al & 2 
BlalSlElS mele leslelsicl| = 3 a 
S| 21 8]8/ 3/86) 8 lea] 318] 2 & 2 B : 
[2 fl elsisieelelesieielsal # 3 - 3 
60 3 g 3 3 a 3 s ‘g 5 3 2 3 g FA a 
El: |+|fl#2/d dale ezia|o/a| 5 a Z 5 
Pterotheca, sp. undetermined............ = 
Pterotheca. sp. undescribed............-. x 
Hyolithes baconi Whitfield.......... : te Be Ss 
Hyolithes, sp. undescribed..............- x 
Hyolithes, sp. undescribed............... x 
Conularia quadrata Walcott............. : x x|x s ae 
Conularia, sp. undescribed............... x Ge 
Conularia trentonensis Hall............. x a 10) TU ae 1) 
Raphistoma peracutum, n. sp............ 940 x ? 
Raphistomina rugata, 0. Sp............-. 944 x 
Omospira alexandra Billings............. 946 + Br BT 
Lophospira bicincta Hall................ 964 x | x x x SB S T BT 
Lophospira obliqua, n. Sp......-.----.-.. 965) x|x XS BEL 
Lophospira concinnula, n. sp..........-. 966 x| x s T 
Lophospira fillmorensis, n. sp........... 967 x 
Lophospira conradana, n. Sp............. 979 x 
Lophospira helicteres var. wisconsin- 
GENS, Io WHPoadac sun sooanpaooudaDoboaE 971 x 
Lophospira quadrisulcata, n. sp.......... 967 x 
Lophospira spironema, 0D. Sp............. 983 x 
Lophospira serrulata Salter.............. 968 x B 
Lophospira perangulata Hall............. 972) x Ss s Ss B 
Lophospira perangulata var. acuminata. 
ib Aes pdad caGecdudo SU sae Aaee eee eee x R 
Lophospira elevata, n. Sp.............-.. 977 x) T ‘ie 
Lophospira peracuta, n. sp.............. 976 x |x s 
Lophospira medialis, n. sp............... 973 x| x oy ay 
Lophospira perforata, n. sp........-----. 984 x | 2x 
Lophospira oweni, 0D. Sp.............----. 980 x | x BU 
Lophospira pulchella, n. sp.............. 982 x xe || SP iG 
Lophospira sumnerensis Safford......... 978 x ay a0 
Lophospira augustina Billings........... 987 x Quebec 
Lophospira augustina var. minnesotensis, 
ity Wilda sioo onivavoe cic mdocs todo Sesneponae Xs 
Lophospira (?) major Hall................ Olax: 
Liospira micula Hall..................... 994 x|x|TULR 
Liospira abrupta, D0. Sp......-......-...5. 995 2 ) ST Ss 
Liospira americana Billings.............. 996 2 x|x ST SBT T BT 
Liospira vitruvia Billings................ 995 x x |x s T BT 
Liospira progne Billings................. 996 x BT ST 13 Ge 
Liospira angustata, 0. Sp................. 997 x x 
Hotomaria dryope Billings............... 1003 x B B 
Hotomaria vicina, n. Sp................. 1003 x 
EHotomaria supracingulata Billings....... 1004 x x Bir 
Clathrospira subconica Hall............. 1006] x | x 2) SaReier sneer T BTH 
Clathrospiraiconica, nm. Sp.--.-...-.----- 1008 x | x xe || Sx 1} aN 1 
Clathrospira convexa, Nn. Sp ............. 1007 x 
Plethospira semele Hall.................. 1010 x 
Hormotoma gracilis Hall................ 1014 x Xa ex: T TH CET 
Hormotoma gracilis var. angustata Hall.}1015 3 SU s Ss B 
Hormotoma gracilis var.multivolvis,a.var}l015 x 
Hormotoma subangulata, 0. sp.......... 1016 3 | 5% 
Hormotoma salteri, n. sp.....+......-... 1016 x i a B 
Hormotoma conferta, n. Sp.........+.++.- x 
Hormotoma bellicincta Hall............. 1017 x a T T 
Coelocaulus cehlerti, n. sp..............-. 1020; . PD || 5x 
Solenospira prisca (?) Billings............ 1022 x S S Cal. 
Solenospira pagoda Salter.... ........... 1022 x = B 
Ophiletina sublaxa, n. sp................ 1030 i |] Ps s 
Ophiletina angularis, 0. sp............-.. 1031 x 
Eccyliopterus owenanus M. & W......... 1032 xe 
Eccyliopterus beloitensis, n. sp.......... 1032 x 
Helicotoma planulata var. robusta, n. var}1033 x 
