138 CHARLES DARWIN 



search the playing passages, and he has known a tobacco- 

 pipe thus recovered. 



The little owl (Athene cunicularia), which has been so 

 often mentioned, on the plains of Buenos Ayres exclusively 

 inhabits the holes of the bizcacha; but in Banda Oriental it 

 is its own workman. During the open day, but more espe- 

 cially in the evening, these birds may be seen in every direc- 

 tion standing frequently by pairs on the hillock near their 

 burrows. If disturbed they either enter the hole, or, utter- 

 ing a shrill harsh cry, move with a remarkably undulatory 

 flight to a short distance, and then turning round, steadily 

 gaze at their pursuer. Occasionally in the evening they may 

 be heard hooting. I found in the stomachs of two which 

 I opened the remains of mice, and I one day saw a small 

 snake killed and carried away. It is said that snakes are 

 their common prey during the daytime. I may here men- 

 tion, as showing on what various kinds of food owls subsist, 

 that a species killed among the islets of the Chonos Archi- 

 pelago, had its stomach full of good-sized crabs. In India* 

 there is a fishing genus of owls, which likewise catches crabs. 



In the evening we crossed the Rio Arrecife on a simple 

 raft made of barrels lashed together, and slept at the post- 

 house on the other side. I this day paid horse-hire for 

 thirty-one leagues; and although the sun was glaring hot I 

 was but little fatigued. When Captain Head talks of riding 

 fifty leagues a day, I do not imagine the distance is equal 

 to 150 English miles. At all events, the thirty-one leagues 

 was only 76 miles in a straight line, and in an open country 

 I should think four additional miles for turnings would be 

 a sufficient allowance. 



2()th and joth. We continued to ride over plains of the 

 same character. At San Nicolas I first saw the noble river 

 of the Parana. At the foot of the cliff on which the town 

 stands, some large vessels were at anchor. Before arriving 

 at Rozario, we crossed the Saladillo, a stream of fine clear 

 running water, but too saline to drink. Rozario is a large 

 town built on a dead level plain, which forms a cliff about 

 sixty feet high over the Parana. The river here is very 

 broad, with many islands, which are low and wooded, as is 

 "Journal of Asiatic Soc., vol. v. p. 363. 



