16 Mr. W.S. Macxeay 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 Anatide 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 czecums, and, finally, in 
the structure of the male organs of generationt, 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 Aigialia, and of Eu- 
chlora to Areodat. 
Let us now form another table of the cervical vertebra, 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 vertebre throughout the class 
* « Facies nuda papillosa Anatis moschate que pre aliis mansuescit et chortalis 
fit videtur Anatis genus ad Gallinas diducere posse.” —Herman. Tab. Aff. p.160. A 
number of concordances in organization between them may be found detailed in the 
Lecons d’ Anat. Comp. 
+ Regne Animal, vol. i. p. 299. 
{ See also Hore 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. Trans. vol. xiv. p. 432). 
1S 
