. A dictionary of birds . of mucus, secreted by the salivaryglands above mentioned, which dries and looks like isinglass. Theirmarketable value depends on their colour and purity, for they areoften intermixed with feathers and other foreign substances. TheSwifts that construct tliese edible nests form a genus Collocalia,of which the number of species is uncertain ; but they inhabitchiefly the islands of the Indian Ocean from the north of MadagascareastAvard, as well as many of the tropical islands of the Pacific sofar as the Marquesas,—one species occurring in the hill-country ofIndia. They br
. A dictionary of birds . of mucus, secreted by the salivaryglands above mentioned, which dries and looks like isinglass. Theirmarketable value depends on their colour and purity, for they areoften intermixed with feathers and other foreign substances. TheSwifts that construct tliese edible nests form a genus Collocalia,of which the number of species is uncertain ; but they inhabitchiefly the islands of the Indian Ocean from the north of MadagascareastAvard, as well as many of the tropical islands of the Pacific sofar as the Marquesas,—one species occurring in the hill-country ofIndia. They breed in caves, to which they resort in great luunbers,and occupy them jointly and yet alternately with Bats—themammals being the lodgers by day and the birds by ^ The genus Cypselus, as noted by Willughby, with its Americanally Panijptila, exhibits a structure of the foot not otherwise ob-served among birds. Not only is the hind-toe constantly directedforwards, but the other three toes depart from the rule which. ACANTHYLLIS. (After Swainson.) Macropteryx. ordinarily governs the number of phalanges in the Birds foot,—arule which applies to even so ancient a form as Archmoijteryx (FossilBirds, p. 278),—and in the tAvo Cypseline genera just named theseries of digital phalanges is 2, 3, 3, 3, instead of 2, 3, 4, 5, whichgenerally obtains in the Class Aces. Other Swifts, however, do notdepart from the normal arrangement, and the exception, remarkableas it is, must not be taken as of more value than is needed for therecognition of two sections or subfamilies admitted by Mr. Sclaterin his monographical essay on the Family [Proc. Zool. Soc. 1865,pp. 593-617^. Mr. Hartert (Cat. B. Br. Mus. xvi. pp. 434-518)recognizes three subfamilies Avith nine genera and 78 geographical distribution is much the same as that of theIlirundinidai (SwALLOW, p. 926); but it should be always and mostclearly borne in mind that, though so like Swallows in many respects,the Swifts
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbirds, bookyear1896
