1()6 PROCEEDINGS OP THE MALACOLOGICAL SOCIETY. 



a certain resemblance to H. cryptophallus in possessing flagella 

 on the epiphallus, and H. maculifer further resembles that species 

 by having a sheath surrounding the penis and part of the epiphallus 

 but excluding both flagella. Pilsbry states, however, that this 

 species has no penis-papilla, a very important distinction. 



The table on p. 107 shows as much as is known about the 

 distribution of some of the more important difierential characters 

 among those species that have been dissected. 



It is clear, then, that there is much diversity in the anatomy 

 of the species found in Tropical Africa, but until a larger number 

 have been adequately described it would be futile to suggest which 

 of the numerous named forms are the most closely related either 

 to H. gomesianus or to H. cryptophallus. Indeed, in our present 

 state of ignorance it is almost impossible to say how the African 

 Helicarioninse should be classified, or into how many distinct 

 genera or subgenera they will probably have to be placed. Never- 

 theless, Pilsbry has recently put forward a tentative classification 

 of the forms with which he is acquainted, " as a basis for further 

 work and criticism." ^ He suggests grouping the species as 

 follows : — 



Genus Africarion, Godwin-Austen. 

 pollens (Morelet), 



Genus Zonitarion, Pfeffer. 

 semimemhranaceus (v. Marts.) (type). 



Genus Mesafricarion, Pilsbry. 

 Subgenus Mesafricarion (s.s.). 



maculifer, Pilsbry (type), Jialiotides (Putzeys), duriformis (Thiele). 



Subgenus Belonarion, Pilsbry. 

 putzeysi, Pilsbry (type). 



Genus Helixarion, Per. 

 Subgenus Granularion, Germain. 

 duporti, Germain (type), wswZans (Thiele), subsucculentus, Pilsbry. 

 stuhlmanni (v. Marts.), issangoensis (Thiele), volkensi (Thiele). 



Subgenus Entagaricus, Pilsbry. 

 entagaricus, Pilsbry (type). 



Subgenus Angustivestis, Pilsbry. 



niger, Pilsbry (type), hequaerti, Pilsbry, ruwenzoriensis, Pilsbry. 



succulentus (v. Marts.), kivuensis (Thiele), schuhotzi (Thiele). 



Genus Gymnarion, Pilsbry. 

 aloysii-sahaudice (Poll.) (type), (?) sowerhyanus (Pfeifier), medjensis 



Pilsbry. 



1 BuU. Amer. Mus. Nat. Hist., vol. xl, 1919, pp. 258-278. 



