94 TURD GALLERY. 



difficulty in rising from the ground. The nesting habits vary greatly 

 in the different genera : the species of Cypselus (1235-1237) (of which 

 our Common Swift is typical) conceal their nests in holes and under 

 eaves; Panyptila (1239) constructs an enormous pendent tube of inter- 

 woven seeds suspended from an overhanging rock by the saliva of the 

 bird; Collocalia (1244-1247) [PI. XX.] builds in caves, the well-known 

 edible nests being composed of dried secretions of the salivary glands ; 

 and Macropteryx (1243) makes a small exposed nest on a branch or 

 stump. The eggs, varying in number from one to five, are invariably 

 pure white and devoid of gloss ; the young are hatched naked. 



To the first subfamily belongs our Common Swift (Cypsdus apus] 

 (1235), which, like most of its allies, is migratory, arriving in Europe 

 early in May and departing to its winter quarters in Africa early in 

 autumn. The Alpine Swift (C. melba) (1236), an occasional visitor to 

 Britain, is a well-known summer visitor to all the high mountains of 

 Central and Southern Europe, breeding in the high crags and towers. 

 The group of old and young birds exhibited in the case were taken 

 from the old tower of the cathedral at Berne, formerly a well-known 

 breeding place, but now replaced by a new spire. The American 

 genera Panyptila (1238) and Aeronautes (1249) have the toes feathered ; 

 the extraordinary nest built by the former has already been referred to. 

 The Palm- Swifts (Tachornis), with the toes naked and arranged in 

 pairs, attach their tiny nests, made of cotton-down and feathers, to the 

 leaves of palms or to the grass roofs of native huts. A nest of 

 T. phcenicobia (1248) is shown in the Case. The Chceturin(B include the 

 Spine- tailed Swifts (Chcetura), with the shafts of the tail-feathers pro- 

 duced into a point or spine. Of these, C. caudacuta (1241), which 

 nests in Siberia and migrates to Australia, is specially interesting, 

 having occurred in Britain on more than one occasion. 



The American genus Cypseloides (1240) calls for no special remark; 

 but the species of Collocalia (1244-1247), ranging from the Indo- 

 Malayan countries to Australia, are interesting on account of their 

 nests, which furnish the birds'-nest soup so much esteemed by the 

 Chinese. As may be seen by the various specimens exhibited in the 

 Case, the nests vary greatly in texture; the best, termed " white " or 

 " first quality," are entirely glutinous and highly prized, while the 

 " brown nests," largely mixed with foreign substances, are considered 

 hardly worth collecting. These birds breed in dark caves in huge 

 colonies, sticking their nests close together on the rocky walls, or even 

 joining them in masses. 



The last subfamily includes only the handsome Crested Swifts 

 (Macropteryx) (1243), ranging from India to Papuasia. Their peculiar 

 nesting habits have been briefly referred to above. The nest is a half- 



