BOOK X. xLvii. 91-XLIX. 94 



dry sea-foam ; and it cannot be discovered of what 

 they are constructed : people think they are made 

 out of the spines of fishes' " prickles, for the birds 

 live on fish. They also go up rivers. They lay five 

 eggs at a time. 



XLVIII. GuUs nest on rocks, divers * also in TheguU. 

 trees. They lay at most three eggs at a time, sea- 

 mews laying in summer and divers at the beginning 

 of spring. 



XLIX. The conformation of the kingfisher's nest Theswai- 

 reminds one of the skill of all the other birds as well ; mrieties and 

 and the i^genuity of birds is in no other department '««^'^.«^* "/ 

 more remarkable. Swallows build with clay and 

 strengthen the nest with straw ; if ever there is a 

 lack of clay, they Avet their wings with a quantity 

 of water and sprinkle it on the dust. The nest 

 itself, however, they carpet with soft feathers and 

 tufts of wool, to warm the eggs and also to prevent 

 it from being hard for the infant chicks. They dole 

 out food in turns among their oifspring with extreme 

 fairness. They remove the chicks' droppings \vith 

 remarkable cleanhness, and teach the older ones to 

 turn round and reheve themselves outside of the nest. 

 There is another kind of swallow <^ that frequents the 

 country and the fields, which seldom nests on houses, 

 and which makes its nest of a diffei-ent shape though 

 of the same matei^ial — entirely turned upward, with 

 orifices projecting to a narrow opening and a capacious 

 interior, and adapted with remarkable skill both to 

 conceal the chicks and to give them a soft bed to 

 lie on. In Egypt, at the Heracleotic Mouth of the 

 Nile, they block the outflow of the river with an 

 irremovable mole of contiguous nests almost two 

 hundred yards long, a thing that could not be achieved 



351 



