HISTORICAL SKETCH. XIX 



were repeated in several subgenera, and it is only by accident that 

 any of them are acceptable iu form. Such names as Hyalina (Hyal- 

 inse Fer.), Heliomanes, etc., cannot date from the Tableaux. The 

 subgeneric divisions of Ferussac's system are based almost wholly 

 upon contour, one of the least stable characters of Helices. The 

 system is, therefore, wholly artificial. Other writers of this epoch 

 are Risso (1826), who by restricting the heterogeneous subgeuera of 

 Ferussac, fixed their types ; Leach, whose subgeneric names are 

 quoted in the synonymy of Turton's work (1831) ; Fitzinger (1833), 

 who proposed generic names for many European groups ; andChar- 

 pentier (1837) who publishes certain names proposed by Agassiz. 

 The latter three authors did not work on Ferussacian lines, but may 

 rather be regarded as foreshadowing the next epoch. 



IV, 1837-1860. BECKIAN EPOCH. A great advame iu Helicol- 

 ogy marked the year 1837. The period of artificial classification 

 waned ; and with the works of HELD and of BECK a new period 

 dawned. Held's work applied only to the European Helices ; but 

 Beck included all known species in his classification. Discarding 

 the arbitrary contour-grouping, Beck formed his subgenera upon the 

 elusive and less striking, but far more stable features of shell struct- 

 ure and texture, form of lip andcolumella, etc. A large proportion 

 of the groups proposed in the Index MoUuscorum are still retained 

 in essentially their original limits. Although founded upon shell 

 characters only, Beck's classification is a vast advance upon previous 

 work; and indicates a mind of rare subtlety and discrimination. 

 During the decade following Beck's publication, several notable 

 works upon Helices appeared. Swainson (1840) attempted to apply 

 the "quinary system," proposing at the same time some new genera. 

 Hartmann (1840-1844) also made additions to the list of names 

 and PFEIFFER, whose name was to be henceforth so intimately asso. 

 ciated with all departments of Pulmonate species-work, published 

 the Symbolse ad Historiam Heliceorum (1841-'42), and in 1848 the 

 first volume of the famous Monographic/, Heliceorum. Pfeiffer's main 

 strength was in the discrimination and concise, explicit, description 

 of species, and in the careful sifting of synonymy ; and in these lines 

 his work has been of incalculable benefit to science. As a systemat- 

 ist his views were not especially original. 



J. E. Gray issued in 1847, a list of genera with their types; and 

 this publication fixes definitely the type species of a number of old 

 genera of Helices, such as Obba, Cochlostyla, etc. 



