TRANSACTIONS OF SECTION D.— DEFT. ZOOLOGY AND BOTANY. 607 



entertained serious doubts as to the validity of tbe Graj-ian arrangement, especially 

 as to tlie groups associated together in the orders Grallte and Anseres, he had been 

 pleased to find available an alternative ^vhich had the sanction of high authority. 

 Whatever might be the case as regards the four principal divisions of the Carinatie, 

 based solely upon the palatal structure, and upon which sundry more or less eflective 

 criticisms had been made by subsequent investigators, there seemed to be no doubt 

 to the author that the minor divisions of the Huxleyan system, by which the 

 whole class of birds was divided into about 23 families, constituted a much more 

 natural system than that of C'uvier and his followers. Prof. Huxley had commenced 

 his system with the lowest and most reptilian birds, and had ended it with the 

 highest and most specialized. But it seemed to the author that by exactly re- 

 versinf' this arrangement he would obtain a scheme which would not very far 

 deviate from that which he had previously employed for the first three orders, 

 and would oiFer many improvements on the Grayian system in the remaining ones. 

 Such a scheme had accordingly been promulgated in the Introduction to the 

 'Nomenclator' and had been used in that work. In the various subsequently issued 

 editions of the 'List of Vertebrated Animals in the Zoological Society's Gardens ' 

 a nearly similar arrangement had been followed. A certain amount of adhesion 

 ha\dng been secured to this system, the author had been recently induced to devote 

 some laboiu- to its improvement and development. As now elaborated it did not 

 profess to be in any respects original, except as regarded certain small details ou 

 points to which he had devoted special attention. The arrangement was in fact 

 simply that of Huxley reversed, with slight modifications consequent upon the 

 recent researches of Parker and Garrod on the anatomy and osteology of little 

 known forms. . 



The author then proceeded to explain further the ' Systema Avium ' thus ad- 

 vocated, as shown in the subjoined table, in which the approximate number of 

 known species was added after each order. 



ORDERS OF EXISTING BIRDS. 



Subclass Carinat^ (10,121 species). 



I 



Subclass Ratitjr (18 species). 

 XXIV. Apteryges ... 4 XXM. Struthiones ... 4 

 XXV. Casuarii . . . . 10 



In submitting this arrangement, as one which on the whole he was disposed to 

 reo-ard as the best to be adopted after many years' study of the Class of Birds, the 

 author observed that it should be recollected that, although a linear system is an 

 absolute necessity for practical use, it could never be a perfectly natural one. It 

 would always be found tliat certain groups were nearly equally related to others in 

 diflfereut places in the linear series, and that it was a matter of difficulty to decide 

 with which of the allied forms they were best located. But, a linear arrangement 

 being an absolute necessity, it liecame our duty to endeavour to make it as natural 

 as possible. 



