GUELPH FAUNA IN THE STATE OF NEW YORK 143 



IG. 



5 The interior of a pedicle valve, with the subdivisions of the 



crescent sharply defined and showing the extent of the 

 cardinal buttress and the low anterior septum. Slightly 

 restored at the umbo. From a gutta-percha impression of 

 the internal cast represented on plate 3, fig. 7 



6 Internal cast of part of the pedicle valve of an old individual, 



showing very strongly marked lateral crescent and platform 

 muscle scars, and short but broad platform vaults 

 All specimens are drawn in natural size and come from 



the Lower Shelby bed at Shelby, Orleans co. N. Y. Originals 



in N. Y. State Museum. 



