FOSSILS OF THE CLINTON GROUP. 565 



9 Crania dubia 



(Plate 87A Figs. 17 a, b.) 



At Soldiers' Home was found a specimen which may possibly have 

 been a Cra?iia. A closely similar specimen from Hanover, Indiana, 

 shows that we are dealing at least with forms of definite shape and size. 

 Xo suriace structure remains. Only the interiors are shown and 

 these do not exhibit muscular scars. Hence it is only possible to say that 

 the identity of these fossils with Crania is within the reach of probability. 

 The shell is convex conical, the apical point is excentric, the valves are 

 broader than long. The regions posterior to the apical point are quite reg- 

 ularly convex, those anterior to the same are much steeper, and in the 

 more median regions show decided flattening. 



The Soldiers' Home specimen is 8 mm. long, and 9 mm. broad. The 

 apical point lies 5.2 mm. from the posterior edge, and about 2 mm. from 

 the anterior line. The convexity of the valve is 2.3 mm. at the apical 

 point. The Hanover, Indiana, specimen is 7.3 mm. long, 9 mm. broad. 

 The apical point is 5.2 mm. from the posterior edge, and about 2 mm. 

 lrom the anterior end. The convexity of the valve is 2 mm. The name 

 ? Crania dubia is suggested. 



'Cat)' 



9 Craniella Clintonensig. 



Plate 37, Fig. 3 a, b.i 



In the collection of Dr. Chas. Welch, at Wilmington, Ohio, collected 

 by his father, is a peculiar cast of a valve, from Todd's Fork, Ohio, which 

 is -very much more satisfactory, inasmuch as it preserves muscular 

 impressions. As regards its relationship to some known genus there is 

 considerable doubt. Possibly it is a Craniella. The accompanying 

 figure is sufficiently explanatory. Its length is 11 mm.) its breath 11.5 

 mm. its convexity is 1.9 mm. The convexity of the shell is quite regular 

 except near the margin where a concave border prevails as shown in the 

 side view. The muscular markings are distinct lor the two upper cir- 

 cular elevations of this cast, and for the upper end of attachment of the 

 lateral sinuous lines. Between the two upper circular elevations is a 

 delta shaped elevation distinct only anteriorly. For this form the name 

 Craniella Cli?itonensis is suggested. 



A single linguloid shell was found in the Clinton, near 

 Dayton, Ohio. It still preserved its phosphatic calcareous shell. The 

 specimen was merely a fragment and would not be worth mention- 

 ing at all, were it not for the fact that it is the sole fragment of a lingu- 

 loid shell so far found in the Clinton of the west. 



