308 Oviposition and Nursing in the Genus Dendrobates. [April 
always lie above a layer of hard rock, on which water accumu- 
lates in the rainy season, soaking the thin layer of loam and turf 
which covers it. At such times there may be half a dozen little 
streams flowing through a spot of varzea over smooth rocks, 
where the subsoil has been washed away; but in the long dry 
season, from May to October, the water evaporates, the ground 
_ dries up and cracks, the grass on it withers, and generally the 
streams disappear. The plants and animals of the varzeas are 
different from those of the rest of the table-land, the species 
being adapted to endure these periodical changes. The place 
that Iam speaking of is quite dry during four or five months of 
every year, and even the ravine at its side has no water; at that 
time the nearest stream is several miles away. 
Wandering over the meadow, now sodden with a recent rain, 
I observed a small frog of a kind which I had frequently seen 
on the varzeas. Some peculiarity in its appearance made me ex- 
amine it more attentively, when, to my astonishment, I saw that 
its back was covered with little black bodies, set close together 
like paving-stones on a street, if I may compare small with large; 
the entire upper surface of the frog, except the head, was con- 
cealed by them. I very quickly saw that these were tadpoles, 
so crowded in the small space that the tails and part of the bodies 
were hidden. They were moist and glistening, as if they had 
just been taken from water, though the sun was shining hotly 
over them. If my observation was correct, they were kept in 
place by a viscid secretion, either from their own bodies or from 
that of the parent. They moved slightly while I was watching 
them. i : 
Up to this time the frog, with its little colony, had remained 
quite still, so that I had a good opportunity to examine it; but 
when I attempted to secure it, it hopped into a patch of grass, 
where, despite of all my searching, I could not find it. I judge 
that it entered some hole among the grass-roots. Heartily appre- 
ciating the fact that a frog in the hand is worth two in the bush, 
_ I was obliged to content myself with an entry in my note-book 
of what I had seen and a resolve to observe the species more 
carefully in future. 
_ I frequently saw the frog after this, but could never get it with 
its young. Nearly a year after, my assistant, Mr. W. C. Smith, 
found a specimen with its colony of tadpoles on a varzea very 
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