Notes on Spirifera Parrvana. 25 



in not a few instances are distinctly rounded and separated by 

 furrows that are as wide as the pHcations themselves. When 

 the shell is exfoliated, even in specimens having the low flat 

 plications with narrow intervening furrows, the ridges on the 

 cast are rounded, and both ridges and furrows are of equal 

 width. This feature is fairly well exhibited to the left of the 

 mesial fold in 8 c. of Meek and Worthen's figures of S. for- 

 nacula already referred to. 



The whole surface of both valves is ornamented with fine 

 radiating striae, and these may be intersected by still finer 

 concentric striae, the result being to impart to the shell a 

 minutely granular appearance. The radiating striae are better 

 developed on some individuals than on others, and in all cases 

 are much stronger on the mesial fold and sinus than elsewhere. 

 The concentric striee are very variable; in some individuals 

 they are quite strong and closely crowded together, and the 

 resulting granular character of the surface is very pronounced. 

 In others they are scarcely visible; in some instances they seem 

 to be entirely absent, and the radiating striae pass apparently 

 without interruption from beak to margin. In a few instances 

 in which the concentric striae are separated by unusually wide 

 intervals and the granules are consequently elongated in the 

 direction of the radiating markings, the granules are highest 

 at their anterior end and closely resemble the bases of set^e or 

 small spines. 



Sfirifera ^arryana seems to be confined to one particular 

 horizon or platform and to have as associates a few species 

 that are confined to the same platform. In the first place it 

 is not associated with our other large spirifer, Spirifera pen- 

 nata^ Owen (not S. -pennata^ Atwater sp.). The two spirifers 

 may be found near together, they may even be found in the 

 same quarry, but so far as I have observed, the beds that 

 furnish S. farryana alwa3^s lie above those in which S. 

 -pennata occurs. This relation of the two series of beds may 

 be readily observed in the quarries at Buffalo in Scott county. 

 Some years ago a small quarry very rich in fossils represent- 



