1927]: Pilsbry-Bequaert, The Aquatic Mollusks of the Belgian Congo A475 
‘seizing the shell by the outer lip, and striking it repeatedly against a 
stone until broken, or fixing the shell in some suitable crevice and pecking 
at it until fractured, a particular stone being often selected to which the 
shells are carried for the purpose of being broken thereon. These sacrifi- 
cial stones known as ‘thrushes’ altars,’ are usually in open positions and 
easily recognized, not only by their slimy surface and the shell-frag- 
ments adherent thereto, but by the little heaps of broken shells which 
are strewn around them.’’! In North America, where the starling is a 
rather recent introduction, this bird does not seem to have taken much 
to a mollusean diet.2 In Australia, too, terrestrial mollusks are but little 
used as food by birds. Cleland’? mentions that on one occasion seven small 
land snails (Nanina marmorata Cox) were found, together with seeds, in 
the stomach of a pigeon, Leucosarcia picata (Latham). 
The following data concerning the molluscan food of birds in the 
Belgian Congo have been kindly furnished by Dr. J. P. Chapin. 
“The gastropods living out of water we found to be preyed upon by 
far more species of birds than were those of aquatic habits. Yet in no 
case was a bird’s diet restricted to mollusks, nor did they ever form any 
large part of its food. In brief, it seemed as though some insectivorou: 
species, and others of mixed diet, occasionally picked up snails or slugs 
along with other organisms; and still less often a seed-eating bird, like a 
ground-dove, or even a fruit-eater, such as a turaco or a barbet, would do 
the same. Passerine birds but seldom ate mollusks, partly because the 
Passeres are more apt to be arboreal, and less likely to come upon snails, 
and still more, I believe, because they find them slimy and distasteful. 
‘More detailed notes from stomach examinations are given under 
the respective species. . 
“Guttera edouardi sethsmithi Neumann. The crops and stomachs of three of 
these blue-spotted Guinea fowl were opened. Two had eaten nothing but manioc 
root, the third had had a more varied meal, consisting of many fruits, some of them 
starchy, 4 small snails, 2 millipedes, a spider, 2 hemipters, 3 large termites, and a large 
ant. 
“Guttera plumifera schubotzi Reichenow. Crops and stomachs of fifteen indi- 
viduals were investigated. In most cases vegetable food predominated, one of the 
most characteristic things eaten being a bright blue, three-chambered seed-capsule 
from some ground-plant. Among the animals eaten, foremost come the snails, 
PUI Tyas tee Sy hk de oe? ete Ce ha oie Ne inl Ry ee 
1Taylor, J. W. 1894-1900. ‘Monograph Land Freshw. Moll. Brit. Isl., Struct. Gen. Vol.,’ (Leeds), 
p. 418. This author figures shells of Helix nemoralis, illustrating the manner in which they are broken 
by thrushes. ; 
is 23ee Kalmbach, E. R., and Gabrielson, I. N. 1921. ‘Economic yalue of the starling in the United 
States.’ U.S. Dept. Agric. Bull. No. 868, pp. 1-66, 1 PI. Mollusks formed but 1% of the annual food 
and were mostly Melampus of the salt marshes, in certain birds along the Connecticut shore. 
3Cleland, J.B. 1918. ‘The food of Australian birds.’ Science Bull. No. 15, Dept. Agric. New South 
Wales, p. 45. 
