Polcontoloffv pf the Cincinnati Croup. 59 



2. P. DAKWiNii, Miller, 1874. 



Upper half of body hemispherical, about 1% inches in di- 

 ameter, lower half slightly depressed, and with a central, cir- 

 cular depression ; the entire outer surface marked by crowded 

 pentagonal and hexagonal depressions, about one line in di- 

 ameter ; frequently compressed and at times covered with a 

 polyzoan ; internal structure unknown. (Cin. Quart. Jour. vSci., 

 vol. I, 1.S74, pp. 5, 6. J\ c/audii, Miller, 1874. Ibid., pp. 6, 7.) 



Localities. — Cincinnati, Ohio, and Maysville, Ky. 



Remarks. — The above two species have been generally con- 

 sidered distinct, but the justice of the separation is doubtful. 

 The general shape is the same in both, as are also the condition 

 of preservation and the form of the external markings. P. 

 globosiis is generally a little the larger; otherwise there is 

 scarcely any difference. P. claudii is doubtless the young 

 form. Its description is : " Body spherical, without any depres- 

 sion where the column or pedicle was attached. Entire sur- 

 face marked by closely crowded pentagonal or hexagonal de- 

 pressions, about 7;V of an inch in diameter. Diameter )^ to ^ 

 of an inch. 



" It differs from P. darwitiii in size, and in having no depres- 

 sion where the pedicle was attached. It is possible that it 

 might be the young of P. darwinii, but at present I think it 

 is a distinct species." It is associated with P. dar^ciiiii at 

 Maysville, Ky. Later investigations do not seem to have 

 changed Mr. Miller's belief that it forms a distinct species, for 

 it is so regarded in his North American Geology and Palae- 

 ontology, 1889, p. 162. 



3. P. (?) TUMiDrs, U. P. James, 1878. 



Hig. ?,—P. y luiitidtts, James. More or less diagraniniatic sketch of the plates on 

 upper surface. 



