518 Systematic Paleontology 



discussed in the general notes under F. ? ciiinherlandica, but P. ? con- 

 centrica seems to be more closely allied to Kirkbya than the former species. 



Occurrence. — Ortskant Formation, Sheiver Member. 21st Bridge. 



Collection. — U. S. National Museum. 



Genus PRIMITIELLA Ulrich 



Primitiella variolata n. sp. 



Plate XCV, Figs. 9, 10 



Description. — Carapace elongate, subquadrate; dorsal margin straight 

 with both ends about equally rounded, the anterior slightly the narrower ; 

 ventral margin almost straight in the middle and but little curved toward 

 the ends ; posterior ventral end somewhat more abruptly curved than the 

 corresponding anterior portion and each but slightly different in curvature 

 from the dorsal ends. Middle third of dorsal half of carapace occupied by 

 a gentle depression. Anterior and posterior ends with a narrow border. 

 Surface marked by more or less regularly arranged small elongate depres- 

 sions or spots averaging six in the length and four in the width of the 

 valve. The anterior portion of the carapace arises abruptly from the mar- 

 ginal rim, but the slope to the posterior edge is gradual ; highest portion 

 of valves in posterior third. 



Length .72 mm. ; height .32 mm. 



The elongate-subquadrate outline and the surface markings are suffi- 

 cient to distinguish this from all other species of the genus. 



Occurrence. — Oriskany Formation, Shriver Member. 21st Bridge. 



Collection. — U. S. National Museum. 



Genus ULRICHIA Jones 



Ulrichia ^qualis n. sp. 



Plate XCV, Fig. 11 



Description. — This neat species is closely related to the type of the 



genus, Ulrichia conradi, described by Jones from the Hamilton shale of 



Canada/ and is probably to be regarded as the progenitor of that form. 



' Quart. Jour. Geol. See. Lond., vol. xlvi, 1S90, p. 544, text fig. 2. 



