474. + Bulletin American Museum of Natural History [Vol. LIT 
amphibians need not search for the few and well-hidden mollusks. ‘The 
‘somewhat larger proportion of mollusks in the stomach contents of the 
several species of Rana was perhaps mostly made up of aquatic snails. 
Leptopelis alone would deserve to be more carefully investigated in 
respect to its molluscan diet. 
Some interesting data on the food of Congo reptiles are given by 
K. P. Schmidt.1 Of the 36 species obtained by Lang and Chapin, only 
four showed molluscan remains in the stomach. They were very rare 
in Agama colonorum Daudin (remains of Subulina in one of 24 stomachs 
examined), Mabuya maculilatris (Gray) (small snails in one of 9 stomachs), 
and M. polytroms Boulenger. On the other hand, Varanus niloticus 
(Linnzeus), the common tropical African monitor, has, in the Congo 
basin at least, largely taken to a molluscan diet, as shown by Lang and 
Chapin’s records of stomach contents. Of five adult specimens of the 
Ituri forest four contained remains of large, crushed land-snails; in two 
cases no other food was present and, in one of these, four specimens of a 
large Achatina filled the stomach. The additional food consisted chiefly 
of crabs, fish, and a water snake. Juvenile monitors contained mostly 
insects, in one case also four large slugs. Observations in other parts of 
Africa have shown that this monitor feeds on a great variety of substances. 
Yet Mr. K . P. Schmidt is of opinion that the strongly modified dentition 
in this species, in which the posterior teeth are developed into broad, 
‘ round crushers, is correlated in the Congo forest with the diet of mollusks 
and crabs.2 It would be of some interest to investigate in how far the 
other tropical African monitor, Varanus exanthemicus (Bosc), in which 
the posterior teeth are much more slender and conical, has a different 
diet. In one of the nine species of Congo chameleons, Chameleon tturien- 
sis Schmidt, a snail was found in one out of three stomachs examined. 
Many insectivorous birds in Europe and North America make land 
mollusks a staple article of their diet during the winter months, this 
being especially true of the starling (Sturnus vulgaris Linneeus), fieldfare 
(Turdus pilaris Linneeus), redwing (7’. cliacus Linnzeus), bearded titmouse 
[Panurus biarmicus (Linneeus)|, reed bunting (Hmberiza scheniclus Lin- 
nus), and titlark (Anthus sp.). It is on such occasions that these 
various song-birds become infected with the flukes that live as cercariz 
in terrestrial snails and slugs (see p. 88). The song thrush (Turdus 
musicus Linneeus), however, feeds at all times largely upon Helices, 
Fweder = sen NN Me Dy EWS REM SATE, no as Ml CM Bor ee tee PERG Oa ekd NUR ETEL by VRE enae iC) ee 
Schmidt, K.P. 1919. ‘Contributions to the herpetology of the Belgian Congo based on the col- 
lection of the American Museum Congo Exepdition, 1909-1915. Part I.” Bull. American Mus. Nat. 
Fist. Noy, XX XIX, pp. 385-624, Pls. vi—-xxx11. 
*See K. P. Schmidt, 1919, Bull. American Mus. Nat. Hist., XX XIX, pp. 488-489. The peculiar 
dentition is illustrated, fig. 104, B. 
