BULIMULID^E. ix 



Draparnaudia, Helicostyla, etc., differ from all Bulimulidce in im- 

 portant features of the pallial organs, genitalia, etc. The same is 

 true of the Partulida and Buliminida, groups closely imitating Buli- 

 mulidcs in the form of the shell. 



All the subfamilies and a large majority of the genera are South 

 American. Two genera, Bulimulus and Drymaus, belonging to the 

 most primitive subfamily of the group, Bulimulina, extend into the 

 West Indies and North America; and two others, Bothriembryon 

 and Placostylus, occur in Australasia, giving testimony to the former 

 existence of an Antartic land connecting the austral continents of 

 the two hemispheres. The other subfamilies are more specialized, 

 and confined to middle and South America. All Odontostomina 

 are South American. The Orthalicince inhabit tropical South 

 America, with two genera, Oxystyla and Liguus, in the Antilles, 

 Mexico and Southern Florida. The subfamily Amphibulimina has 

 the same distribution, two genera being Antillean and Mexican, two 

 South American. 



The past history of the Bulimulidse is still most obscure. The 

 numerous modifications of the group, and its omnipresence in South 

 America lead us to believe it an old group there, and probably it 

 arose in that region. Its advent in continental North America has 

 obviously been a recent incursion from the South, and the Austra- 

 lasian groups also are emigrants from South America. But while 

 its chief characteristics must have been well established in Cretaceous 

 or Jurassic times, there is yet no trace of Bulimulidse in Africa. 

 This is somewhat remarkable because a former land connection with 

 Africa through the mid- Atlantic, as claimed by Koken ancfothers, is 

 emphatically proclaimed by the Streptaxidae, Achatinidde (Neobetis- 

 cus, etc.), Amputtariidde, freshwater fishes, etc., of South America. 

 This is altogether independent of the problematic connection of 

 South Africa and Antarctica, claimed by certain naturalists, and 

 supported to some extent by the dominence of Endodontidse of 

 Austral types in the Cape region and St. Helena. 



Classification of Bulimulidse. 



The family may be divided into four subfamilies, as follows : 

 I. BULIMULINJE. Shell usually perforate or umbilicate, usually 

 ovate, rarely cylindrical or Helicoid; generally rather small, 

 the aperture toothless. Jaw with vertical or converging 

 plaits. Teeth of the normal Helicid type or variously 

 modified. Genitalia without accessory organs. 



