8 Doll — 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 Sphcerium, 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, 1S12; Arctiea 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. 



