GrRABAU — 



Faunas of the Hamilton Group. 



259 



Genus Sphenotus, Hall. 



62. Sphenotus truncatus, Conrad. 



1885, Hall, Pal. N. Y., vol. 5, pt. 1, p. 394, pi. 65. 



A small right valve, having the form and markings of this species was 

 obtained from the S. demissa bed. The dimensions are: length 9 mm., height 

 4.5 mm. 



Genus Conocardium, Bronn. 



63. CONOCARDIUM, Sp. 



Two or three species of Conocardium occur in the upper Encrinal lime- 

 stone. The material obtained is so crushed and broken, and the shell so 

 frequently dissolved, that it is impossible to make specific determinations.* 



Genus Lunulicardium, Minister. 



64. Lunulicardium fragile, Hall. 



1885, Hall, Pal. N. Y., vol. 5, pt. 1, p. 434, pi. 71. 



A single left valve of this species was found in the Hamilton shales about 

 ten feet below the Encrinal limestone (Section B). The greater portion of 

 the test is gone, but the remaining portion shows the fine concentric stria 1 . 

 The cast shows faint radiating striatums. The dimensions of the specimen 

 are : height, 1 1 mm., length, 9.75 mm. This species, though extremely rare in 

 the typical Hamilton shales, is not of uncommon occurrence in the transition 

 shales, and becomes progressively more abundant as we approach the Marcel- 

 lus shales. 



Genus Pholadella, Hall. 



65. Pholadella radiata, Conrad. 



1885, Hall, Pal. N. Y., vol. 5, pt. 1, p. 469, pi. 78, 96. 



This species was described as occurring in some concretionary layers at 

 Eighteen-mile creek. 1 have found it in the Modioniorpha subcdata bed, and in 

 the shale about ten feet below the Encrinal limestone (Section B). 



*More recent study has shown the presence of C uormaie. Hall, aad C eboraccum. Hall, among the fragments collected 

 from the Encrinal limestone. 



