1927] Pilbsry-Bequaert, The Aquatic Mollusks of the Belgian Congo 479 
“Sitagra tenioptera txenioptera (Reichenbach). <A yellow weaver, fond of river 
banks in the northern savanna. The diet is of seeds and insects, mixed; and our 
finding a bit of mollusk shell in one of the 9 stomachs examined is no proof that 
this bird had done more than swallow it to help in grinding its food.” 
Among the Mammalia many of the rodents are accused of regaling 
themselves upon land snails. Field mice (Arvicolide), in Europe and 
North America, consume large quantities of Mollusca, mainly Helices, 
breaking into the shell by gnawing away the side of the whor! in quite a 
characteristic fashion. Broken shells are often thickly strewn along their 
runways.! Rats, hedgehogs (Hrinaceus europeus Linneeus), foxes, and 
even rabbits are believed to devour Helices, especially in winter, and some 
of the rodents even burrow into thick snow to gain access to hibernating 
snails. We know of no African mammal that shows a decided predilec- 
tion for mollusks. In East Africa the common mongoose, Mungos 
mungo (Gmelin), an omnivorous animal, is said to include snails in its 
diet. According to Bohm? it breaks these by lifting them up in the fore- 
paws and dashing them down upon a hard object. 
Man himself should not be forgotten, for in some parts of the world 
land snails are an important item of his diet. The taste for this kind of 
food has always been highly developed in the countries surrounding the 
Mediterranean and it is quite possible that it has caused the total extince- 
tion of a number of species within historic times. At any rate, M. Pal- 
lary, who for many years has assiduously studied the snail fauna of Oran, 
told the junior author that in that vicinity some of the larger, local Helici- 
dee have within the last twenty years become exceedingly rare or prac- 
tically extinct, due to heavy consumption by the Spanish settlers. 
According to H. Lang,’ in all regions visited by him in the Belgian 
Congo, the large snails of the genus Achatina “at times furnish a welcome 
addition to the food supply of most tribes, and in the Uele are served 
occasionally at the table of Europeans.” He also describes the native 
method of preparing them. | 
Zoogeographic Divisions of the Ethiopian Region 
In the following ecological study of the distribution of land mollusks 
in the Congo we shall accept the seven main biogeographic districts into 
which our territory has recently been divided by J. P. Chapin.* Although 
these divisions were primarily based upon a-study of birds, they neverthe- 
iSee J. W. Taylor, 1894-1900, ‘Monograph Land Freshw. Moll. Brit. Isl., Struct. Gen. Vol.,’ 
(Leeds), p. 417, where the manner in which field-mice destroy Helzces is illustrated. 
2Quoted by T. Noack, 1887, Zool. Jahrb., Abt. Syst., II, p. 254. 
81919, Bull. American Mus. Nat. Hist., XL, p. 56. ibe 6 : ae ; 
4J. P. Chapin. 1923. ‘Ecological aspects of bird distribution in tropical Africa.’ American 
Naturalist, LVII, pp. 106-125. 
