170 Trans. Acad. Sci. of St. Louis. 



at least occasionally, finely plicate within throughout its length. 

 The species described by Dr. Dall from the Florida Pliocene 

 under the name pygmaea, will probably form a genus or sub- 

 o-enus different from the purely lyrate species including 

 cincta Dall from the same beds, as well as lirata Ad., as- 

 sumed as the type of Mitro7nor]Dha. This genus has recently 

 been assigned to the Mitridae by Dall (Trans. Wag. Inst., 

 Vol. 3, p. 95). 



Issued May 19, 1904. 



