1890.] -= The Evolution of Mina. 1001 
similar nest, but of a larger and less solid character. The interior 
remains semi-fluid, and the eggs hatch and the young pass there 
a part atleast of their larval life before dropping into the stream 
below. The region is not subject to drought, so that the object 
of this habit may be to escape enemies which may lurk in the 
water. 
In South America certain Hylidæ (Notrotrema, Opisthodelphys) 
and Pipide (Pipa) adopt the habit of placing the eggs on the 
back. The former mostly inhabit a region which zuffers from 
drought,—the western slope of the Andes. They retain the eggs 
in an invagination of the dorsal integument until they are hatched, 
and in some cases until they have passed their metamorphosis. 
In the genus Dendrobates (Dendrobatidz), also South Ameri- 
can, the tadpoles are carried over land on the back of the parent, 
attached by their mouths, to a new pond, when the old one dries 
up. The most peculiar modification is that adopted by the 
Rhinöderma darwini of Chili (fam. Phryniscide). The male 
takes the eggs into his vocal sac, which is entered from the floor 
of the mouth. This sac is greatly extended in this species, 
reaching below the entire abdomen. Here the eggs hatch, and 
the tadpoles remain till such time as they complete their meta- 
morphosis. As in the stickleback and the catfish, this is a case 
of paternal instinct. 
The intelligent efforts of certain birds to divert the attention of 
enemies from their nests are well known. Two prominent cases of 
this kind in North America are the woodcock (Philohela minor), 
and the oven bird (Szurus aurocapillus). The flutterings of these 
birds along the ground, apparently in easy reach of the grasp of the 
pursuer, lead the latter far from the nest. When safety is assured, 
the bird flies away unharmed. The two species mentioned have no 
zoological affinity with each other, so that they have adopted the 
habit independently. 
In the capture of prey animals often show a remarkable knowl- 
edge of the physical characters of the latter. Thus the ophio- 
phagous snakes seize venomous species by the muzzle, thus 
keeping their mouths closed and preventing their biting. The 
wonderful habits of the species of mud-wasps in this respect 
