VI CYPSELIDAE 423 
tionally short tail; C. wsshert of the Gold Coast is dark brown, 
varied with a good deal of white; C. cassini of the Congo and 
Gaboon, and C. boehmi of Kast Equatorial Africa, are glossy black 
with less white. C. acuta of the West Indies, C. grandidieri of 
Madagascar, and other forms, complete the genus. 
In Cypseloides 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. brunneitorques. 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, 
being 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 joming them in masses; the materials may include 
moss, straw, lichen, and so forth, but inspissated saliva is the 
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 worth 
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. fuciphaga, which 
obtained its specific name from the erroneous idea that it built 
1 Green, J. Physiol. vi. 1885, pp. 41-45. 
