248 



Report of the State Geologist. 



Genus Platyostoma, Conrad. 

 = Diaphorostoma, P. Fischer. 

 24. Platyostoma (Diaphorostoma) lixeatum, Conrad. 

 1879, Hall, Pal. N. Y., vol. 5, pt. 2, p. 21, pi. 10. 



1885, Paul Fischer, Manuel de Conchyliologie, p. 756. 

 This is the most abundant gasteropod in the Hamilton group of this 

 region. It is comparative!}" rare in the shales and limestones between the 

 Trilobite beds and the Strophalosia bed, and has not been observed below 

 the latter. A single small but perfect specimen was found in the lowest 

 Trilobite bed. It is abundant in the uppermost one foot of the Hamilton shales, 

 but all the specimens are small. It is fairly abundant in the Encrinal lime- 

 stone, and is also 1fhe best preserved gasteropod of that rock. It occurs 

 sparingly in the lower Moscow shales. The specimens from the limestone 

 are all very much larger than the shale specimens, these latter being all 

 undersized. The surface markings are usually obliterated in the limestone 

 specimens but show beautifully in most of the specimens from the shale. 



Genus Euomphalus, Sowerby. 



25. Euomphalus ^Phajsterotunts) laxus, Hall. 



1879, Hall, Pal. N. Y., vol. 5, pt. 2, p. 60, pL 16. 



A fragment showing the circular tube, gradual enlargement, and loose 

 coiling of this species was found in the Encrinal limestone. It has not been 

 found in the shales above or below, but occurs in the upper layers of the 

 Marcellus sha-le, and in the lower portion of the transition beds. 



26. Euomphalus (Straparollus) eudis, Hall. 



1879, Hall, Pal. N. Y., vol 5, pt. 2, p. 58, pi. 16. 



A closely coiled speeimen with the shell removed, was found in the 

 Encrinal limestone. 



Genus Pleurotomaria, Defiance. 



27. Pleurotomaria Lucina, Hall. 



1879, Hall, Pal. X. Y., vol. 5, pt. 2, p. 67, pL 18. 



Several casts from the Encrinal limestone are referred to this species. 

 The)- show the flattened revolving band characteristic of this form. 



