Silurian Fossils. 19 



much smaller size, occurs in the West Union bed in the quarry 

 in the southeastern corner of West Union, Ohio. These 

 specimens agree fairly well with some of the pauciplicate forms 

 illustrated by Hall, in volume 2 of the Paleontology of Xew 

 York, but not with the multiplicate forms illustrated by Hall 

 and Clarke in volume 8 of the same series. As far as may be 

 determined by a comparison with the figures accompanying 

 the original description, our specimen is more strongly 

 plicated. 



Whitfieldella xitida. Hall. 



Specimens not exceeding 15 mm. in length ; the cast of 

 the brachial valve marked by a distinct median septum ex- 

 tending 3 mm. from the beak;- the cast of the pedicel valve 

 showing the presence of two vertical dental lamell?e, without 

 any strongly developed muscular impressions. A faint median 

 depression marks the anterior margin of the pedicel valve. 



West Union bed, at the spring on Big Salt Lick Creek, 

 one mile above Glen Springs, and at Harin Hill, four miles 

 west of \'alley, in Lewis county. Kentucky. Also at the 

 Cjuarry in the southeastern part of \\>st L^nion, Ohio. 



\\'hitfieldella erecta, sp. nov. 

 Plate I. Figs. 9 A. B, C. 



Shell small. The largest specimen found so far has a 

 length of 9 mm., a width of 9.5 mm., and a thickness of -i.5 

 mi'm. The outline of the pedicel valve is rounded ovate ; that 

 of the brachial valve is more nearly circular. The valves are 

 approximately equally convex, the convexity being moderate 

 in the case of smaller valves but increasing with age. A 

 median depression becomes distinct about 3 mm. from the 

 beak and increases in width and depth anteriorly, though 

 remaining rather shallow and comparatively narrow. Most 

 of the brachial valves are evenly convex, but occasionally 

 a valve is found which has a faint median depression anteri- 

 orly. The beak of the pedicel valve is short and erect ; it does 



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