VI CYPSELIDAE 423 



tionally short tail ; C. ussheri of the Gold Coast is dark brown, 

 varied with a good deal of white ; C. cassini of the Congo and 

 Gaboon, and C. hoelimi of East Equatorial Africa, are glossy black 

 with less white. C. acuta of the AVest Indies, C. granclidieri of 

 Madagascar, and other forms, complete the genus. 



In Ci/2Jseloicles the shafts of the rectrices scarcely project per- 

 ceptibly ; while the tail is emarginate in C. niger of western 

 North America, the Antilles, and Guiana. The coloration is plain 

 black or brown, with a reddish collar round the neck in the males 

 of C. rutilus and C. h^unneitorques. The genus ranges to Peru 

 and Brazil. The nest, placed in holes in houses and so forth, is 

 made of straw, leaves, and rubbish : the eggs are four or five. 



Collocalia is an especially interesting section of the Family, on 

 account of the nests furnishing the birds'-nest soup of the Chinese. 

 Being formed of the dried secretions of the salivary glands,^ these 

 are almost entirely glutinous, and when newly built are termed 

 " white " or " first quality." The thirteen diminutive species are 

 black or brown above, occasionally with a blue gloss, and white 

 on the rump or tail ; the under parts being whitish or grey. 

 They are not migratory, but extend over most of the Indian 

 and Australian regions, except the northernmost portions, 

 beino; found as far south as North Australia. One form reaches 

 the Mascarene Islands. Huge numbers breed in company in 

 dark caves, sticking their nests close together upon the rocky 

 walls, or even joining them in masses ; the materials may include 

 moss, straw, lichen, and so forth, but inspissated saliva is tlie 

 chief, and often the only, constituent, especially in C. fuciphaga. 

 " Brown nests " are those discoloured by use, or spoilt by an 

 admixture of foreign substances, and are considered hardly w^orth 

 collecting. Two eggs are the usual complement. The caverns 

 are entered from boats below, or by ladders from above, other 

 ladders or poles notched for the feet being fixed in the rocky 

 flooring of the interior. These are ascended by natives armed 

 with long-pronged forks, who obtain hundreds of nests at one 

 gathering. Bats occupy the caves by day, the birds by night or 

 when incubating ; while at any time the noise of the escaping 

 denizens is almost deafening. The breeding sites are a very 

 lucrative property. The especially valuable C. fucipliaga, which 

 obtained its specific name from the erroneous idea that it built 

 ' Green, J. Physiol, vi. 188."), pp. 41-45. 



