Fig 32.— GASTKRorODS.— a, Platyceras .Himosum ; i, P. angulatum ; c, Platyostoma Niaga- 
rensU- J, Cithara M ississippiensis ; t, Murchisonia bcllicincta ; /, M. bicincta; ft Uaphistoma 
lentirnbris • h. 1 Myotonia plamilnta ; I, Plcurotomaria tabulata ; /, P. spham.lata ; Mncrn- 
chcilus fusiform* J I, Dentalium MississippienM. 1 1 BtTOOrOI* -«, Ecoilion.plu.llis Trenton- 
, Cyrtolitcs comprcssus ; o and /, Bellerophon bilobatus ; B. carbonanus. 
ensis ! n. 
Examples of Gasteropoda may be found under nearly every 
epoch represented. The most noted ones are in the Chazy, Case 
b, Sect. 1 1 ; Trenton, Case c, Sects. 3, 4 and 1 1 ; New York 
and Western Niagara, Case e, Sect. 13. Some peculiar ones in 
the Guelph, Case f, Sect. 8 ; Lower Helderberg, Case O, Sect. 2 ; 
Oriskany, Case 6, Sects. 7 and 8 ; Lower Helderberg, Case h, 
