170 Annals of the Carnf.gie Museum. 



Actinoptera decussata Hall. 



Pal. N. Y., Vol. V, pi. I, p. Ill, pis. 17, 18, 20, 84. 



This species is very rare, and only one good specimen was obtained. 

 That is 12 mm. high and 19 mm. long. It shows the usual surface 

 markings, the concentric ridges being high and sharp. The species 

 is reported as rare in the Encrinal and above it at Eighteen Mile 

 Creek and Cayuga Lake, and common in both at Livonia. 



Aviculopecten exacutiis Hall. 



Pal. N. Y., Vol. V, pt. I, p. 8, pi. iii. 



All our specimens of this shell are small and fragmentary. The 

 largest is 17 mm. high. The species is fairly common in the lower 

 part of the Hamilton at Eighteen Mile Creek and in the upper part at 

 Livonia. It is not reported further east. 



Aviculopecten princeps Conrad. 



Pal. N. Y., Vol. V, pt. I, p. I, pis. I, 5, 6, 24, 81. 



This species is more common than any of the other lamellibranchs 

 in the present faunule and reaches more nearly its normal size. The 

 largest specimen is 57 mm. high and about 70 mm. long. The species 

 is fcurly common in all the sections except the extreme eastern and 

 western ones. It is very rare at Thedford and does not occur in the 

 eastern counties except at a fevv localities. 



Aviculopecteii scabridiis Hall. 



Pal. N. Y. Vol. V. pt. I, p. 7, pi. 3. 



The individuals of this species obtain a fair size at this locality. 

 The largest is 28 mm. high. The species is common in the upper 

 Hamilton at Livonia and is rare at Canandaigua Lake and in the lower 

 Hamilton at Cayuga Lake. It is not reported from the other sections. 



Pterineopccten micrmediiis Hall. 



Pal. N. Y., Vol. V, pt. I, p. 68, pis. 17, 83. 



The one well preserved specimen in the collection shows the usual 

 characters, though it is of small size, 14 mm. high. 



The species is rare at Cayuga Lake, which is the only one of the 

 sections from which it is reported. 



Pterineopecteri hermes Hall. 



Pal. N. Y., Vol. V, pt. I, p. 64, pi. 17. 



The largest specimen of this species in the collection is 16 mm. 

 high. It is rare here, as also at Eighteen Mile Creek and Cayuga 

 Lake. It is not reported elsewhere. 



