8 Dall Revision of Cyrenacea. 



schen Region' have been accepted in determining the synonymy of the 

 types. 



It may be of interest to state here that the group Cyclas, a name ap 

 plied by Bruguiere, in 1798, to a heterogeneous assembly, and afterward 

 used by Lamarck for species of the prior genus Spharium, was first 

 properly divided by Link in 1807, who segregated Musculium and took 

 the largest and first species of Bruguiere as a type for the genus Cyclas. 

 This was the Venus islandica of Linne*, to which, subsequently, the 

 names of Cyprina Lamarck, 1812; Arctica Schumacher, 1817, not Moeh- 

 ring, 1758; and Cypriniadea Rovereto, 1900, were applied. These be 

 come synonyms of Cyclas (Bruguiere) Link, whose only species and type 

 is Venus islandica L. 



