DESCRIPTION OF SPECIES 183 



Description. Specimens of Pustula pertenuis have been obtained 

 from the Sharon ore and the Lower Mercer and McArthur limestones, 

 although they are of rare occurrence in the Pottsville rocks of this State. 

 The small size, the fine radiating lines, and the numerous concentric 

 wrinkles which cover the entire shell, together with a few scattered 

 spine bases make the form easily recognizable. 



Dimensions. A specimen from the Harrison ore measures: length 

 8 mm., width 11 mm., convexity 4 mm. 



Horizon and locality. Sharon ore: Scioto County, Locality 2, r. 

 Lower Mercer member: Muskingum County, Locality 28, r,; Licking 

 County, Locality 46, r. McArthur member: Jackson County, Local- 

 ity 80, r. 



Pustula punctatus (Martin) 

 PL VIII, fig. 9 



1836 Productus punctatus ? Morton, Am. Jour. Sci., 1st Ser., Vol. 29, p. 153, PI. 26, 



Fig. 38. 



Coal Measures: Ohio Valley. 

 1838 Producta semipunctata. Shepard, Am. Jour. Sci., 1st Ser., Vol. 34, p. 153, Fig. 9. 



Limestone: Peru, Illinois. 



Description. Pustula punctatus is common in the Pottsville forma- 

 tion of this State in and above the Boggs member. It is generally 

 well preserved and can be distinguished by its large size and by the 

 numerous regular, concentric ridges covered with small spines which 

 mark the surface. An almost perfect specimen from the Boggs lime- 

 stone has the following measurements: length 40 mm., length of hinge 

 line 30 =*= mm., width 38 mm., convexity 22 mm. 



Horizon and locality. Boggs member: Muskingum County, Lo- 

 calities 27, 28, r. Lower Mercer member: Muskingum County, Locali- 

 ties 44, 45, r; Licking County, Localities 46, 48, 49, c. Upper Mercer 

 member: Muskingum County, Locality 21, r. 



Pustula symmetricus (McChesney) 







PI. VIII, fig. 7 



1860 Productus symmetricus. McChesney, Desc New Pal. Foss., p. 35. 



Upper Coal Measures: LaSalle and Springfield, Illinois. 

 1865 Productus symmetricus. McChesney, 111. New Spec. Foss., PI. 1, Figs. 9a-b. 



Description. Representatives of Pustula symmetricus are rare in 

 the collections of Pottsville fossils at hand and consist of a few dorsal 

 valves from the Lower and Upper Mercer members. These differ 

 from the dorsal valves of P. nebraskensis principally in their larger size 

 and in their trifid cardinal process, which in the latter species is bifid. 



