OF CONCHOLOGY. 



,227 



ON THE LIMPETS; WITH SPECIAL REFERENCE TO THE 

 SPECIES OF THE WEST COAST OF AMERICA, AND TO A 

 MORE NATURAL CLASSIFICATION OF THE GROUP. 



BY W. H. DALL, SMITHSONIAN INSTITUTION. 



Malacologists have long felt the need of a revision of the Cy- 

 clohrancMata (5f Cuvier. In this paper the results of a careful 

 examination of a large number of species are detailed, and an 

 approximation to a more natural classification of the Limpets 

 has been attempted. The task has been by no means easy, yet 

 it is hoped that some light has been thrown upon the subject, 

 and the way made easier for the application of information 

 which may be gleaned in the same field by other authors. 



Historical Notes on the Nomenclature. 



Throwing out the more incongruous forms which were in- 

 cluded in the genus Patella of Linnseus, we find the majority of 

 the patelliform shells included by Cuvier (1817) in his order Cy- 

 clohrancJdata. Lamarck (1818) placed them among his Pliylli- 

 diens. Ferussac (1819) with a clearer perception of their char- 

 acters, adopting Cyclohranchiata as the name of an order, formed 

 for the Patellidce a suborder, Schismobranchia* placing the 

 chitons in another, which he called, after Blainville, Polyplaxi- 

 phora.-f 



Latreille (1825) divided the Cyclohranchiata into two families, 

 [Scutiformes and Lamelles) corresponding to the sub-orders of 

 Ferussac, except that in the former he unwisely included with 

 the Patellae, the genus Umbracidum, Schum. ( Umbrella, Lam.) 



Blainville, in the same year, used the terms Schismohranchia- 

 ta and Cyclobranchiata, to include heterogeneous and unnatural 

 groups of other mollusks, while he formed an order, Cervicobran- 



*Not Schismobranchia, Blainv. ,Schismobrancluata, Blainville, Risso ; 

 nor Schismatobranchia, Gray. 



t Afterwards corrected by Gray to Polyplacophora. 



