Remarks on Some Fossils of the Cincinnati Group. 1 7 



very rapid and short curvature upon the edge of the specimen, on 

 the dorsal side, so as to meet the ridged row of plates, and joining 

 with it in zigzag manner of overlapping tiling, as seen in figure C, 

 Avhich is a dorsal view. This small curvature of the flat row of 

 plates has a flat extension beyond it, as seen in figure C and E. 

 Upon this extension the small slope of the ridged row of plates 

 rests, with its edge against this small curvature. Thus these two 

 rows lie in zigzag manner over each other, thereby making a very 

 firm holding. This small extension exists even in the basal curva- 

 ture. 



I consider Figure 2. of Hall and Whitfieki's Pluiiiulitcs jamesi, 

 as one of this flat row of plates, wi'rh this small extension broken 

 away, but still leaving the curvature, and also broken away from 

 this general depression shown in my Figure B, in the center of 

 the specimen. Figure E shows these characters well, but the reader 

 must not imagine that these can be seen in one view, as these are 

 curved in under the plate so as to meet the other row, the curva- 

 ture representing the space between the first and second line drawn 

 from the apex of the plate, while the small extension represents the 

 space between the second line and the edge of the ])late. The flat 

 row is more characteristic in having scallops than the ridged row. 

 These two rows meet each other at the ventral side like a knife 

 edge. Here it undoubtedly had the power of opening. 



The plates of these rows bear the same markings as Plumulites^ 

 but differ greatly in form. These plates, L. jainesi, are the same in 

 form, but being reverse to each other in the roundings of the lower 

 extremity of the plates, as seen in figure E and D. 



Figure F is a dorso-ventral section of the specimen, showing 

 the three unequal sides. 



The specimen figured by Mr.' S. A. Miller I consider as the 

 ridged row of plates, the ridge which separated the plates being 

 broken But as this specimen was not seen, I can not be positive, 

 also I do not consider the figure as very exact. 



The beautiful specimea here described Avas collected by Mr. 

 Charles Wessels, in the Cincinnati Group about 150 feet above low 

 water mark in the Ohio River at Cincinnati, and is now in the 

 Author's collection. 



CyCLOCYSTOIDES NITIDUS, 710V Sp. 

 Plate I. Figure i. 



This specimen has a complete ring, composed of twenty-four 

 marginal plates, which are somewhat elongate. The specimen is a 



