ON THE PROGRESS AND PRESENT STATE OP ORNITHOLOGY. 209 



by Prof. Purkinje, under the title of ' Symbolse ad Ovi Avium Historian!,' 

 Leipzig, 1830. The structure of the viiellus has been investigated by M. 

 Pouche (Comptes Rendus, 1839), and that of the umbilical cord by M. Flou- 

 rens (Institut, 1835, p. 324), while M. Serres has described the branchial re- 

 spiration of the embryo of mammifers and birds in the ' Ann. Sc. Nat.,' ser. 2. 

 vol. xiii. p. 141. 



Closely connected with oology is the subject of nidification, one of the 

 most interesting branches of ornithological observation, and one which often 

 throws important light on questions of natural affinities. I am not aware of 

 any special work on this subject except the ' Darstellung der Fortpflanzung 

 der Vogel Europa's,' by Thienemann, and the popular 'Architecture of Birds' 

 by the late Prof. Rennie, but the details of the nidification of European birds 

 are contained in most of the works which treat upon them. The nests of the 

 majority of exotic species are still unknown, though Wilson, Audubon, Gould 

 and others have in some measure suppHed this deficiency in our knowledge. 



The songs and call-notes of birds are very important in their relation to 

 habits and affinities, though from the imperfect mode of indicating these 

 sounds by alphabetical or musical characters, there is much difficulty attend- 

 ing their study. In some cases, such as the relation of Phyllopneuste rufa to 

 P. trochilus, or of Corvus corone to C. americanus, the notes of the living 

 birds present clearer specific distinctions than are shown by their physical 

 structure, and the melody of the woods thus becomes no less interesting to 

 the scientific zoologist than it is fascinating to the unlearned lover of nature. 



External Terminology. — The series of terms employed by Brisson, Lin- 

 naeus and Latham, in describing the external parts of birds, were greatly im- 

 proved in precision and accuracy by the ' Prodromus Systematis Mammalium 

 et Avium' of Illiger. His series of descriptive terms are still generally cur- 

 rent, and have undergone comparatively little change. Definitions and figures 

 illustrative of the terms employed in ornithology will be found in most general 

 treatises on the subject, among which Lichtenstein's ' Verzeichniss der Dou- 

 bletten,' Berlin, 1823, Stephens's 'General Zoology,' Swainson's ' Classifi- 

 cation of Birds,' Wilson's article Ornithology in ' Encyclopasdia Britannica,' 

 the article Birds in the ' Penny Cyclopaedia,' and M'Gillivray's ' History of 

 British Birds,' may be mentioned as being useful guides to the language of 

 descriptive ornithology. 



There is an excellent summary of the different characters used for orni- 

 thological classification, and of the due value to be attached to them, by M. 

 LGeoffroy St. Hilaire, in the 'Nouv. Ann. Mus. Nat. Hist.' 1832, and in the 

 ' Essais de Zoologie Generale' of the same author, 1841. He shows that the 

 value of the emarginated upper mandible, of the feathers and of the caruncles 

 has been much overrated, and points out that the structure of the tongue, the 

 wing and the toes, furnishes characters which have not been duly appreciated. 

 The importance of the feet, as indicating natural affinities by their structural 

 details, is further insisted on by M. de Lafresnaye in the ' Magazin de 

 Zoologie.' 



7- Fossil Ornithology. 



Our knowledge of Birds has received a less amount of extension from the 

 discoveries of PalEeontology than perhaps that of any other class of the animal 

 kingdom. Not only are the fossil remains of birds of considerable rarity, and 

 confined principally to the most recent deposits, but when found, they seldom 

 present characters of such a nature as would enable us to predicate generic, 

 much less specific, differences. The generic characters of birds being mostly 

 drawn froni the structure of the corneous appendages of the skin, such as 

 1844. p 



