the Land and Freshwater Shells of Bar'hados. 249 



111 the case of the Streptaxis^ Bulimus ohlongus^ perhaps of 

 all the Bulimuli, the Orthalicus, the Planorbls, and the Palu- 

 destrinaj we may conjecture that they have spread northward 

 to the islands, from the fact that those genera are more 

 numerous in species on the mainland. On the other hand, 

 we may suppose that the Stenogyrai and the Leptinaria have 

 migrated southward from the islands to the continent, as the 

 species in question, Leptinaria lamellata, St. octona, and St. 

 Beckiana, appear, as far as we know at present, to be more 

 common in the islands. This is somewhat conjectural, as our 

 knowledge respecting the distribution of any of these species 

 is doubtlessly very incomplete, and we do not know the 

 relative abundance of them in the various localities where 

 they have been found. 



Bulimus ohlongiis and the Orthalicus are said to have been 

 introduced by direct personal agency, and in all probability 

 the presence of others is attributable to the same cause. The 

 introduction of trees and plants from one place to another 

 atfords an easy way for the transmission of land-shells either 

 in tiie egg-stage or even as adult specimens. 



1. Vitrea incisa {VioxWer) . 



Helix incisa, PfeifFer, Mai. Blatt. 18(36, vol. xiii. p, 78 ; Monogr. Hel. 

 vol. V. p. 107. 



Hab. Barbados. 



This species was described from Barbados from specimens 

 obtained by Mr. Theodore Gill. It is a very de])ressed form, 

 with a flattened spire, and remarkable for the distinct impressed 

 lines of growth which divide the last whorl into numerous 

 seameuts. 



2. Helix [Dentellaria) perplexa^ Fdrussac. 



Helix jierplexa, Ferussac, Hist. nat. Moll. vol. i. p. 378, pi. Ivi. a. 

 fig. 1. 

 • Helix yranifcra, Gray, Pfeiffer, Conch.-Cab. ed. 2, pi. Ixii. figs. 10, 17; 

 Reeve, Conch. Icon. pi. lii. figs. 252 a, b, pi. clxxvii. fig. 1210 (as 

 per/jlexa). 



Llab. Grenada, Trinidad?, Barbados. 



This species has not been previously recorded from Bar- 

 bados ; but some specimens, presented to the British Museum 

 by iSir Kawson iiawson in 1870, were said to have come from 

 that locality. 



