224 Zoological Society. 
tilope it is assumed by every writer on the subject to be a natural 
group, even whilst they confess that it has not a single character 
either exclusively appropriate to it or even common to the generality 
of its component species: far, therefore, from being a natural, it is 
not even entitled to be considered an artificial group. The diagnosis 
proposed by M. Geoffroy St. Hilaire regarding the nature of the core 
of the horns, and that broached at a meeting of the Zoological So- 
ciety by M. Agassiz, to the effect that these animals are distinguished 
from Bos, Ovis, and Capra, by having a spiral twist of the horns 
turning from left to right, instead of the opposite direction, are 
founded upon hasty generalizations, inapplicable to at least three- 
fourths of the species. 
The form or curvature of the horns, the beard, the dewlap, the 
scope, the number of teats, and other such diagnoses hitherto em- 
ployed to define the genera of Ruminants, according to the views of 
Mr. Ogilby, are purely trivial and accidental characters, which not 
only exercise no assignable influence on the habits or economy of 
the animals, but which may be modified to any extent, or even 
destroyed altogether, without in the slightest degree changing the 
generic relations. 
Having demonstrated the Oi cetacraed of the actual distribution 
of hollow-horned Ruminants, Mr. Ogilby proceeds to the exposition 
of the principles which he proposes to make use of for that purpose, 
and to explain the nature and extent of his own researches. He in- 
sists upon the law of classification, that no generic characters should 
be admitted but. such as are founded upon the necessary relations 
that subsist between the organic structure of animals and their 
habits and economy. 
The next section of the monograph is devoted to the consideration 
of the horns of the Ruminantia. Under this head the author first 
treats of their substance ; 2ndly, their permanent or deciduous cha- 
racter ; 3rdly, their presence or absence in different genera and sexes ; 
and 4thly, their number, forms, and flexures. 
The distinctions between the horns of the stag tribe generally, 
and those of the hollow-horned Ruminants, are pointed out, and in 
the next place the various modifications observable in the horns 
and their core of the latter group. ‘‘In some cases the substance 
of this bony core is solid, or at least penetrated only by minute 
pores; in others, and they are by far the greater number, it is par- 
tially hollow, or filled with large cancelli, which communicate with 
the frontal sinuses. These variations are not confined to any par- 
ticular groups, but are equally common to solid and hollow-horned 
genera. The giraffe, for instance, has very extensive cancelli; so 
likewise have the oxen, sheep, goats, and all the larger species 
hitherto classed among the antelopes: nor have I found the solid 
core, so much insisted on by MM. Cuvier and Geoffroy St. Hilaire, 
in any of these animals, except the A. Cervicapra, the Dorcas, and 
their allied species.” 
Speaking of the raised ridges and annuli on the horns, Mr. Ogilby 
states that the number of these added in a given time appears to be 
