1888.] NATURAL SCIENCES OF PHILADELPHIA. 241 



AcUs robusta Meek and Worthen, 1873. Geol. 111., vol. V, p. 

 596. 



Abundant. This and the preceding species were described by 

 Stevens under Aclis, but in 1881 de Koniuck established the genus 

 Aclmna which now includes the four American carboniferous species 

 originally described under the former genus. 



Streptacis whitfieldi Meek. 



Streptacis whitfieldi Meek, 1871. Proc. Acad. Nat. Sci. Phila., p. 



173. 

 Streptacis xoUtfieldi Meek and Worthen, 1873. Geol. 111., vol. 



V, p. 596. 

 This species is very rare, and is found associated with the four 

 preceding species. 

 Anomphalus rotulus Meek and Worthen. 



Anomphalus rotulus Meek and Worthen, 1866. Proc. Acad. 



Nat. Sci. Phila., p. 268. 

 Anomphalus rotulus Meek and Worthen, 1873. Geol. 111., vol. 



V, p. 597. 

 One of the most abundant species occurring in superimposing 

 shales of coal No. 3. In some of the specimens there is a tendency 

 to become angular around the periphery toward the terminus of the 

 body-whorl. 

 Euomphalus rugosus Hall. 



Euomphalus rugosus Hall, 1858. Geol. Iowa, vol. I, p. 722. 

 Straparollus (Euomphalus) subrugosus Meek and Worthen, 1873. 



Geol. 111., vol. V, p. 607. 

 Euomphalus rugosus White, 1884. 13th Kep. Geol. Indiana, p. 



161. 

 This species is quite common. 



Euomphalus pernodosus Meek and Worthen. 



Straparollus (Euomphalus) pernodosus Meek and Worthen, 1870. 



Proc. Acad. Nat. Sci. Phila., p. 45. 

 Straparollus (Euomj^halus) pernodosus Meek and Worthen, 1873. 



Geol. 111., vol. V, p. 604. 

 But a single specimen of this large Euomphalus has been found 

 at Des Moines. 



