V. 



HISTORICAL SKETCH OF 

 CLASSIFICATIONS 



IX THE EARLY VOLU:\IES on the IMollusca, the planorbids, as well 

 as other genera, were largely classified by the shells and were placed 

 in families with wide limits as to the genera involved. Thus in 1851- 

 1856, in S. P. Woodward's Manual of the Mollusca, nearly all of the 

 genera of fresh-water pulmonates — Limnaea, Chilina, Physa, Planorbis, 

 and Ancylus — appear in the family Limnaeidae. In A History of British 

 Mollusca, by Forbes and Hanley, in 1853 (volume iv) the fresh-water 

 pulmonates of the genera Limnaea, Planorbis, Physa, and Ancylus are all 

 placed in the family Limnaeidae. 



AV. G. Binney, in 1865, published a work on The Land and Fresh-Water 

 Shells of North America, in which the fresh-water pulmonates are all 

 placed in the family Limnaeidae with Limnaeinae, Planorbinae, and Ancy- 

 linae as subfamilies, Physa being included in the subfamily Linmaeinae. 



Li 1870, W. H. Dall proposed a classification in which four subfamilies 

 were recognized: Limnaeinae, Planorbinae, Camptocercinae, and Pom- 

 pholiginae. In 1872, George W. Tryon, Jr., in a Monograph of the Fresh- 

 icater Univalve Mollusca of the United States, placed all groups under 

 the family Physidae, but separated the principal groups as subfamilies: 

 Limnaeinae, Pompholiginae, ^legasystrophinae, Planorbinae, and An- 

 cylinae. In this grouping he was following Haldeman ( 1842-1844) who 

 |)laced Planorbis and other groups in the family Physidae. 



Paul Fischer, in the Manuel de Conchyliologic (1883), listed most of 

 the fresh-water pulmonates under the family Limnaeidae, within which he 

 recognized Ancylinae, Limnaeinae, and Planorbinae as subfamilies. Physa 

 he relegated to a separate family. Tryon, a year later (1884), in the third 

 volume of his Structural and Systematic Conchology, placed all of the 

 fresh-water pulmonates under the family Limnaeidae with subfamilies 

 Limnaeinae (including Physa, Aplexa, Bulinus, etc.), Pompholiginae, 

 Planorbinae, and Ancylinae. A. H. Cooke, in 1895, evidently following 

 Paul Fischer, separated Physidae as a family but places the subfamilies 

 Limnaeinae, Planorbinae, and Ancylinae in the Limnaeidae. F. C. Baker 

 in 1902 and Dall in 1905 separated Physa and Aplexa to form the family 

 Physidae but placed Limnaea [Lymnaea) , Planorbis, and allied genera in 

 the family Limnaeidae. Ancylus was made a separate family, Ancylidae, 

 by Baker. 



In 1902, Westerlund placed all of the Basommatophorous mollusks in 

 the family Limnaeidae with four subfamilies, Limnaeinae, Physinae, 

 Planorbinae, and Ancylinae. Dybowski (1903) proposed a classification of 

 tlie Basommatophora in which six families were recognized, Limnaeidae, 

 Limnophysidae, Amphipeplidae, Planorbidae, Ancylidae, and Physidae. 

 Bryant "Walker ( 1918) in his 'Synopsis' recognized four families, Lym- 

 naeidae, Planorbidae, Physidae, and Ancylidae. 



From 1920 onward, most of the important monographs and lists have 

 accepted the four-family division of the Basommatophora, Lymnaeidae. 

 Planorbidae, Physidae, and Ancylidae (Germain. 1921-23; Kennard and 



41 



