20 Cincinnati Society of Natural History. 



not curve over the beak of the brachial valve, but exposes the 

 unclosed triangular delthyrium. The surface of the shell is 

 smooth. The number of volutions of the spires forming the 

 brachidium is about 7 ; the remainder of the brachidium has 

 not been observed. 



Kokomo limestone at Kokomo, Indiana; common in the 

 Traction quarry, but found also in the old George W. Defen- 

 baugh quarry. 



The exposure of the delthyrium even in mature specimens 

 is the chief diagnostic characteristic of this species, although 

 this feature is shared by WhitfieldeUa didyuia from the Silu- 

 rian of Gotland. This characteristic probably will serve to 

 distinguish the Kokomo species from WhitfieldeUa nucleolata, 

 which it otherwise resembles. The more conspicuous depres- 

 sion along the median part of the pedicel valve, anteriorly, 

 and the absence of concentric striae also are distinguishing 

 features. 



Anoplotheca congregata. Kindle. 



A small species of Anoplotheca, differing from the form 

 described by Kindle from Logansport, Indiana, only in its 

 much smaller size, occurs abundantly in the Traction quarry, 

 and in. smaller numbers also in the upper part of the old 

 George W. Defenbaugh cjuarry, at Kokomo, Indiana. 



Leptaena rhomboidalis, IVilckens. 



Width 22 mm., length estimated at 13 mm. ; with 11 or 12 

 concentric wrinkles, of which the anterior 4 or 5 are rather 

 prominent. Six or seven radiating strise in a width of 2 mm. 



West Union bed, at the bluff northwest of Martins, also at 

 Harin Hill, four miles west of Valley, in Lewis county, Ken- 

 tucky. A similar specimen, from the spring a mile south of 

 Glen Springs, on Big Salt Lick creek, appears to be more 

 coarsely striated. 



A very small form of Leptccna rhomboidalis, about 12 mm. 

 in width, occurs both at the Traction and at the old George 

 W. Defenbaugh quarry, at Kokomo, Indiana. 



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