164 Annals of the Carnegie Museum. 



fold of the dorsal valve is always divided by a median depressed line. 

 The largest specimen is 14.8x52 mm. This type is found also in 

 eastern New York, East Bethany, Eighteen Mile Creek and Thedford, 

 Ont., but in all those localities there are other varieties associated 

 with it. 



S. audactiliis Conrad. 



Pal. N. Y., Vol. IV., 1867, p. 227, pi. 38. 



The specimens of .S". audaculits are few, and smaller than the usual 

 adult size of this shell. The species is rare at Thedford, but common 

 in the other sections. It usually is most common in the upper zones 

 east of Eighteen Mile Creek. 



S. granulosus Conrad. 



Pal. N. Y., Vol. IV., 1867, p. 223, pi. 36. 



In the lower zones at Eighteen Mile Creek and in certain localities 

 in the upper Hamilton of Otsego Co., this species is very common. 

 At Livonia and Canandaigua Lake it is rare, and it is likewise uncom- 

 mon in "Albany and Scoharie Counties. 



Delthyris consobrijius d'Orbigny. 



Pal. N. Y., Vol. IV., 1867, p. 222, pi. 35. 



This species showed the usual characters, but some specimens had 

 so few plications as to approach D. sculptis in character. The species 

 has not been reported either from Thedford or eastern New York. It 

 is common in this faunule, as it is in two of the zones above the En- 

 crinal at Eighteen Mile Creek. It was not reported from Livonia 

 and is not common at Cayuga Lake except in a couple of zones near 

 the to]) of the section. 



Delthyris sculptis Hall. 



Pal. N. Y., Vol. IV., 1867, p. 221, pi. 35. 



Two or three well preserved specimens of this species were obtained 

 which showed the usual strong plications. The vertical range of this 

 species does not seem to be very great. At Thedford and Eighteen 

 Mile Creek it is confined to the Encrinal limestone, and at Cayuga 

 Lake it occurs in only one zone (D). At Livonia it occurs above the 

 Encrinal, as it does at Canandaigua Lake. 



Reticularia fnnhriata Conrad. 



Pal. N. Y., Vol. IV, 1867, p. 214, pi. 33. 



This species has been found from Thedford to Otsego Co., but it is 

 usually rare in the various localities, as it is in this faunule. 



