1895.] OP SOME TEEE-FKOGS OF BEAZIL. 91 



surrounded by a wall of mud — nurseries for the tadpoles. Nine o£ 

 these nests or pools may be seen on the figure, and I shall describe 

 how we witnessed their formation and subsequent use. 



For the purpose of cleaning and deepening, the pond had been 

 nearly emptied the year before and was kept in this state till the 

 beginning of 1894, the water in the centre being no more than 

 from 3 to 4 feet deep. In the first days of February we noticed 

 some newly made walled pools every morning. We had to wait for 

 full moonlight to make our observations. 



On the night of the 18th February, between 9 and 11 o'clock, 

 we approached the pond, occupied, as we could hear from a 

 distance, by at least a dozen of the large Tree-Frogs. The moon 

 was shining brightly, and much favoured our undertaking, but 

 even under these circumstances we had to accustom our sight to 

 discern the details in the marginal vegetation and the portions 

 somewhat hidden in the shadow. By and by we discovered the 

 " ferreiros," some at work, othei's drumming together on the walls 

 of some pool or in the middle of the pond, sittiug upon some 

 floating object, such as water-plants. The vocalists, the mode- 

 rately inflated subgular vocal sacs of which we could distinguish, 

 were males. 



We were posted on the side where the nests nos. 1 to 5 are to 

 be seen. From a distance not greater than 2 to 3 feet we could 

 survey, with all desirable distinctness, the rising of nest no. 3. 

 On that place we first saw some slight movement in the water, 

 produced by something stirring below the surface. We then soon 

 saw a mass of mud rising to the surface carried by a Tree-Frog, 

 of which no more than the two hands emerged. Diving again, 

 after a moment's time, the frog brought up a second mass of mud, 

 near the first. This was repeated many times, the result being 

 the gradual erection of a circular wall. From time to time the 

 builder's head and front part of body appeared suddenly with 

 a load of mud on some opposite point. But what astonished us 

 in the highest degree was the manner in which it used its hands 

 for smoothing the inside of the mud wall, as would a mason with 

 his trowel. And by examining the hands of Hyla faher it will 

 readily be understood that they must act as excellent trowels, 

 the terminal phalanges supporting very large expansions. This 

 careful smoothening could be better observed as the wall got 

 higher, until it reached about four inches, and the Tree-Frog was 

 then obhged to get out of the water. The parapet of the wall 

 receives the same careful smoothening, but the outside is neglected. 

 The levelling of the bottom is obtained by tlie action of the lower 

 surface (belly and throat principally) together with that of the 

 hands. We can well compare the aspect of the pool to the crater 

 of an extinct volcano or a large porringer filled with water, 

 measuring nearly a foot in diameter and generally of a very 

 regular circular form. 



Now we have to record another observation, made with the 

 most positive certainty, viz., that the male frog is present during 



