ON THE PROGRESS AND PRESENT STATE OP ORNITHOLOGY. 205 



In Dr. Grant's ' Outlines of Comparative Anatomy,' the structure of birds 

 is described with the same accuracy as that of the other classes of animals ; 

 but as the work is arranged anatomically and not zoologically, the details of 

 ornithic anatomy are necessarily intermixed with those of the other classes of 

 animals. 



Prof. Rymer Jones has given, in his ' General Outline of the Animal King- 

 dom,' a careful abstract of the anatomy of Birds, including more especially 

 the structure of the eye and the important subject of the development of the 

 ovum. The excellent mode in which the generalities of the subject are 

 treated of, makes us regret that the limits of Prof. Jones's work prevent him 

 from giving a fuller statement of the anatomical characters of the several 

 orders and families. 



An excellent synopsis of this subject is contained in Wagner's 'Compara- 

 tive Anatomy,' of which Mr. Tulk has just published an English translation. 



Of special treatises, either on the anatomy of particular organs throughout 

 the whole class, or on the general anatomy of particular groups, many are to 

 be found scattered over the field of scientific literature, and I shall notice 

 some of the more important. 



The general subject of the jmeumaticity or circulation of air through the 

 bodies of birds is ably treated of by M. E. Jacquemin in the ' Nova Acta 

 Acad. Caes. Leop. Car.' 1842. See also 'L'Institut' and 'Comptes Rendus,' 

 1836. After minutely describing the modifications of the aerating system in 

 different forms of birds, the author deduces a series of conclusions, and shows 

 that this structure, peculiar to the class of birds, performs the fourfold office 

 of oxidizing the blood, — of enlarging the surface of the body, and conse- 

 quently the points of muscular attachment, — of diminishing the specific gra- 

 vity, and of producing a general elasticity which favours the act of flight. 



The structure of the ear in birds is treated of in great detail in a memoir 

 by M. Breschet, in the ' Annales des Sciences Naturelles' for 1836, and in a 

 detached treatise on the same subject. After giving an historical sketch of 

 the researches of previous authors, he enters upon an elaborate description of 

 the characters of this organ in various groups of birds. He shows that of 

 the three bones of the tympanum, the stapes alone is osseous in birds, while 

 the malleus and the incus, which in Mammalia are composed of bone, are 

 here represented by cartilaginous processes, and he points out many other 

 minute but important characters which appear to distinguish the ears of birds 

 from those of other Vertebrata. 



Dr. Krohn has treated on the organization of the iris, and Dr. Bergman on 

 the movements of the radius and ulna in MuUer's ' Archiv fiir Anatomic,' 

 18S7-9. 



The structure of the os hyoides in birds, and the affinities of its several 

 parts to the corresponding organs of the other Vertebrata, are explained in a 

 memoir by M. Geoffroy St. Hilaire, in the ' Nouvelles Annales du Mus. d'Hist. 

 Nat.' 1832. 



M. Miiller has described the modifications of the male organs of birds in 

 the ' Abhandlungen der Akad. der Wissenschafteu zu Berlin,' 1836. 



M. Cornay, in ' Comptes Rendus,' 1844, p. 94, has announced that he finds 

 an important character to exist in the anterior palatine bone, the modifica- 

 tions of which in the various orders he considers to form a more correct 

 basis of classification than any one hitherto employed. Until more attention 

 be paid to this organ than it has yet received, it would be premature to pro- 

 nounce as to the value of it. 



The gradual development of ossification in the sternum of young birds, 

 and the relations of its several parts to the skeletons of other Vertebrata, were 



