BKLOGONA. 175 



later authors. The American forms have been studied by W. G. 

 Binney, but as many of his figures are of doubtful accuracy my con- 

 clusions have been based wholly upon fresh dissections. The West 

 Indian genera are herein for the first time made known anatomic- 

 ally ; and the forms of East Asia are partially known by the work 

 of Semper, but largely by my own dissections. The great mass of 

 data before me from these sources, has compelled me to reject von 

 Ihering's phylogenetic scheme, and to offer the following arrange- 

 ment : 



BELOGONA EUADENIA. Mucus gland one, inserted on dart sack 

 or at its base ; simple or divided, glandular, sacculated, globular or 

 bulbous. 



BELOGONA SIPHONADENIA. Mucus glands usually two or many, 

 inserted on vagina ; tubular or composed of tubular branches. 



Apparent exceptions to this arrangement are seen in Helicigona 

 quimperiana, where the tubes are shortened into hollow, thin-walled 

 sacks, and some Fruticicoloid forms with demonstrably degenerate 

 genitalia. The first of these divisions will now be discussed : 



BELOGONA EUADENIA. 



This division of the Belogona, characterized by having mucus 

 glands of typically glandular structure, in contradistinction to the 

 tube-like glands of the Siphonadenia, is now distributed throughout 

 Eastern Asia, outlying groups extending to New Guinea and the 

 Solomon Is., and northward to Japan and Siberia. In America it 

 occupies the Pacific slope from British Columbia to Argentina, with 

 genera in the Greater Antilles. It is a significant fact that its area 

 while in large part coincident with that of the Epiphallogona 

 (Hadra, Camcena, Obba, etc.) is over stepped on nearly all sides by 

 the latter. Thus Planispira extends further west in India ; Thers- 

 ites (+ Hadra) and Chloritis extend beyond it southward to Aus- 

 tralia ; Papuina has a far greater range throughout the " Melanes- 

 ian Plateau " ; and Ganesella follows the Euadenia to the confines 

 imposed by rigorous climate in the north. And in the New World, 

 again, while both Euadenia and Epiphallogona have a wide range 

 in South America, the latter are universally dispersed throughout 

 the Caribbees as well as the Greater Antilles, whilst the former came 

 too late to follow them to the Caribean chain. The inference is, of 

 course, that the Kpiphallogona are an older faunal element, and 

 have had more time to take advantage of the various means of dis- 

 persal by which islands (especially continental islands) and conti- 

 nents have been peopled. 



