DESCRIPTION OP SPECIES 263 



anterior canal on the outer lip, have been placed under the genus 

 Sphaerodoma. Specifically they have been referred rather doubtfully 

 to S. humilis, which they seem to resemble closely in contour. Height 

 5.5 mm., height of body whorl 3 mm., width of body whorl 3 mm. 



Horizon and locality. Harrison ore: Jackson County, Locality 1, c. 



Sphaerodoma newberryi (Stevens) 



1858 Loxonema newberryi. Stevens, Am. Jour. Sci., 2nd Ser., Vol. 25, p. 259. 

 Coal Measures: Danville, Illinois. 



Remarks. About six specimens from the Lower Mercer and 

 McArthur limestones in a fairly good state of preservation are in very 

 close agreement with Sphaerodoma newberryi in size, number and shape 

 of volutions, and in the height and slope of the spire. The fold on the 

 columnella is distinctly shown. 



Dimensions. A specimen of average size measures: height of 

 shell 31 mm,, height of body whorl 19 mm., width of body whorl 13.5 mm. 



Horizon and locality. Lower Mercer limestone: Perry County, 

 Locality 35, r. McArthur limestone: Vinton County, Localities 83 (r), 

 84 (c). 



Sphaerodoma primigenia (Conrad) 



1835 Stylifer primigenia. Conrad, Trans. Geol. Soc. Penn., Vol. 1, p. 267, PI. 12, 



Fig. 2. 

 1915 Sphaerodoma primigenia. Girty, U. S. Geol. Surv., Bull. 544, p. 208, PI. XXIV, 



Figs. 13-17a. 



Wewoka formation : Oklahoma. 



Remarks. A single internal cast of a small gastropod from the 

 Sharon ore has been placed with the above species. As may be seen 

 from the following measurements, the form from the Sharon ore is 

 much smaller than even small specimens of Sphaerodoma primigenia: 

 height 12 mm., height of body whorl 7 mm., width of body whorl 10 mm. 



A few rather well preserved specimens from the Lower Mercer and 

 McArthur limestones have been assigned to the same species more 

 confidently. They are about twice the size of the individual from the 

 Sharon ore and resemble S. brevis somewhat closely, but may be dis- 

 tinguished by their larger size and broader spire, the sides of which are 

 straight, not concave as in the latter species. 



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

 Lower Mercer limestone: Perry County, Locality 35, r. McArthur 

 limestone: Vinton County, Locality 84, c. 



