538 Bulletin American Museum of Natural History [Vol. LIII 
bill, the bird first crushes the shell between its mandibles. Dr. Bequaert observed 
this procedure by captive birds. In fact the gaping form of the beak is plainly the 
result of constant wear on the tomia, using up the horny sheath of the mandibles, 
and exposing a deep fibrous layer which forms a sort of brushy pad and tends to give a 
firmer grip on the smooth shells. The curved outlines of culmen and gonys, together 
with the greater hardness of the sheath in those regions, are responsible for the meeting 
of the mandibles at their tips. 
“The shells of fresh-water mussels are probably too stout to be crushed in the 
beak of Anastomus, for such competent observers as Heuglin and Bohm have stated 
that the bird brings them out to the bank, allowing them to lie there until they open 
of their own accord. Although the open-bill has been said to eat other aquatic ani- 
mals, and even insects, there can be no question as to the preponderance of mollusks 
in its diet. 
‘“Hagedashia hagedash nilotica Neumann. The hadadah ibis is primarily an 
insect feeder, probing in the mud with its long bill; and I have found as many as 18 
mole-crickets in a single stomach. Heuglin has described it as feeding on snails, but 
in the few stomachs we examined the only molluscan’ remains consisted of a single 
fragment of shell. 
‘“ Pieronetta hartlaubi (Cassin). Ducks are so scarce, in all the forested districts 
of the Congo, that evidence as to the proportion of Mollusca in their food is hardly 
satisfactory. Hartlaub’s teal is the one duck characteristic of the region; and of the 
ten stomachs examined, six held only coarse sand, with no identifiable food remains. 
Of the four remaining birds, one had eaten 24 aquatic insect larve (mainly of dragon- 
flies, some about two inches long); another, similar larve plus 8 fresh-water snails 
with hard conical shells; a third had taken a spider, a shrimp, and two tiny bivalve 
mollusks; and the fourth many small seeds. 
‘Of the seven other species of Anatide we collected, only 18 individuals were 
secured, none of which had any mollusk remains in the stomach. 
“Himantornis hematopus whitesidei Sharpe. The large brown wood rail of 
Congo forests is hardly a bird of aquatic habits, and I am in doubt whether the small 
snails we found in the stomach of one individual were water-living forms. Six other 
birds were examined without our finding any sign of mollusks, five stomachs contain- 
ing varied insect remains, and two some hardshelled yellow seeds. 
“Canirallus oculeus Hartlaub. This second wood rail is little more aquatic than 
the preceding. In three stomachs examined we found pebbles, small snails (in two 
cases),.slugs (in one), a small crab, a green caterpillar, and other insect remains. So 
far as it goes, the evidence shows a considerable proportion of molluscan food. 
“Podica senegalensis senegalensis (Vieillot). The finfoot seldom if ever dives, 
and is not a fish eater. In the seven stomachs we examined there were invariably 
remains of insects (beetles, a green grasshopper, a dragon-fly larva, and wings of a 
dragon-fly). One of the birds had also eaten a small crab, another 2 snails, small 
shrimps, and a millipede. 
‘Charadrius hiaticula Linneus. Only a migrant to tropical Africa. The stomach 
of a ring plover taken at Faradje in the Upper Uele district was found to contain 
many freshly hatched flies, a small beetle, several tiny clam-like bivalves, a very 
small snail, and a millipede. | 
“Tringa ochropus Linneus. The green sandpiper is another migrant from 
Eurasia. One of the two stomachs we examined held pieces of mollusk shell, whereas 
the other had pieces of fresh-water shrimps and insects. 
