Birds offer in some respects better evidence than quadrupeds, from their breeding more rapidly and being kept in greater numbers. (18/29. A list of the species of birds which have bred in the Zoological Gardens from 1848 to 1867 inclusive has been published by Mr. Sclater in 'Proc. Zoolog. Soc.' 1869 page 626, since the first edition of this work appeared. Of Columbae 51 species have been kept, and of Anseres 80 species, and in both these families 1 species in 2.6 have bred at least once in the 20 years. Of Gallinae 83 species have been kept and 1 in 27 have bred; of 57 Grallae 1 in 9 have bred; of 110 Prehensores 1 in 22 have bred; of 178 Passeres 1 in 25.4 have bred; of 94 Accipitres 1 in 47 have bred; of 25 Picariae and of 35 Herodiones not one species in either group has bred.) We have seen that carnivorous animals are more fertile under confinement than most other mammals. The reverse holds good with carnivorous birds. It is said (18/30. 'Encyclop. of Rural Sports' page 691.) that as many as eighteen species have been used in Europe for hawking, and several others in Persia and India (18/31. According to Sir A. Burnes 'Cabool' etc. page 51, eight species are used for hawking in Sinde.); they have been kept in their native country in the finest condition, and have been flown during six, eight, or nine years (18/32. Loudon's 'Mag. of Nat. Hist.' volume 6 1833 page 110.); yet there is no record of their having ever produced young. As these birds were formerly caught whilst young, at great expense, being imported from Iceland, Norway, and Sweden, there can be little doubt that, if possible, they would have been propagated. In the Jardin des Plantes, no bird of prey has been known to couple. (18/33. F. Cuvier 'Annal. du Museum' tome 9 page 128.) No hawk, vulture, or owl has ever produced fertile eggs in the Zoological Gardens, or in the old Surrey Gardens, with the exception, in the former place on one occasion, of a condor and a kite (Milvus niger). Yet several species, namely, the Aquila fusca, Haliaetus leucocephalus, Falco tinnunculus, F. subbuteo, and Buteo vulgaris, have been seen to couple in the Zoological Gardens. Mr. Morris (18/34. 'The Zoologist' volume 7-8 1849-50 page 2648.) mentions as a unique fact that a kestrel (Falco tinnunculus) bred in an aviary. The one kind of owl which has been known to couple in the Zoological Gardens was the Eagle Owl (Bubo maximus); and this species shows a special inclination to breed in captivity; for a pair at Arundel Castle, kept more nearly in a state of nature "than ever fell to the lot of an animal deprived of its liberty" (18/35. Knox 'Ornithological Rambles in Sussex' page 91.), actually reared their young. Mr. Gurney has given another instance of this same owl breeding in confinement; and he records the case of a second species of owl, the Strix passerina, breeding in captivity. (18/36. 'The Zoologist' volume 7-8 1849-50 page 2566; volume 9-10 1851-2 page 3207.)