16 Mr. W. S. Macleay on the Comparative Anatomy 



latter 56. Now there is also some relation indubitably existing 

 between these two birds, which may serve to account in some 

 degree for that general connexion which almost every observer 

 must have remarked between the Anatida and Gallinaceous 

 birds*. On comparing the Ostrich and the Swan, we notice, 

 that different as they are in their economy, in the structure of 

 their feet, and even general form, they nevertheless present an ap- 

 proximation in the length of neck, form of beak, vegetable food, 

 enormous crop, muscular gizzard, long caecums, and, finally, in 

 the structure of the male organs of generation t, so different 

 from those of all other families of birds. These two similar 

 relations existing between the Raptores and Rasores on the 

 one hand, and between the Natatores and Rasores on the other, 

 may appear extraordinary : but it would be inconsistent with 

 what I believe to be the general plan of Nature, did they not 

 obviously occur to us; for the opposite points of a circle of 

 affinity always exhibit such alliances, as I first observed in the 

 approximation of the genus Hybosorus to jEgialia, and of Eu- 

 chlora to Areoda %. 



Let us now form another table of the cervical vertebrae, from 

 the same data that enabled us to produce the last ; previously to 

 which, however, I may remark, that it is a curious characteristic 

 of the Mammalia, that, with the exception of one species, (where 

 it is 9,) the number of cervical vertebrae throughout the class 



• " Facies nuda papillosa Anatis moschata quae pras aliis mansuescit et chortalis 

 fit videtur Anatis genus ad Gallinas diducere posse." — Herman. Tab. Aff. p. IfiO. A 

 number of concordances in organization between tliem may be found detailed in the 

 Lefons d^Anat. Comp. 



t B^gne Animal, vol. i. p. 299- 



% See also Hora Entom. p. 319 and p. 403, where this relation is more developed. 

 It is the Affinity of Transultation of M . Agardh (see Linn. Trans, vol. xiv. p. 50.), 

 which Mr. Vigors has so well applied to account for the relation existing between the 

 Fissirostral and Scansorial tribes of Insessores. (See Linn. Tram. vol. xiv. p. 432). 



is 



