328 GEOGRAPHICAL DISTRIBUTION 
whether it melts insensibly into that of the Nearctic area of the 
Holarctic Region. It will be most convenient to consider that 
Region next, though strong doubts may be entertained as to the 
logical propriety of such a course, for this Holarctic Region seems 
to have the most highly developed Fauna, in that it is one from 
which the weakest types have generally been eliminated, though 
that result is chiefly seen in its Palearctic area, and perhaps espe- 
cially in the western part of this, shewing the truth of the poet’s 
line happily applied by Mr. Sclater in his classical essay— 
“Better fifty years of Europe than a cycle of Cathay.” 
IV. The Holarctic Region-—As has been stated in the introduc- 
tory portion of this article, the combination intimated by this 
phrase, though sanctioned in spirit by Prof. Huxley, wholly con- 
travenes the opinion expressed by two of the leading authorities 
on the subject—Messrs. Sclater and Wallace. The arguments of 
the former being based on positive facts, or at least on what seemed 
at the time to be such, must be met by corresponding facts. Those 
of the latter having a more hypothetical foundation—the notion 
that each of the primary divisions of the earth’s surface should 
comprehend about the same extent—require less consideration. 
The natural philosopher regards quality rather than quantity, and 
things must be weighed as well as measured, analyzed as well as 
surveyed. Scarcely any systematist nowadays doubts that among 
Mammals the Monotremes, of which only two living Families are 
known, form a Subclass at least as important as the Monodelphians, 
the existing members of which may number nearly fourscore Families, 
even if there be not an opinion that Monotremes are of equal rank 
(in one sense of the word) with the Monodelphians and Didelphians 
thereto added. But, not to wander from our present business, no 
one who will investigate the Avifauna of that part of North: America 
lying outside the boundary (if it can ever be traced) of the 
Neotropical Region, will find in the Nearctic area more than a 
single Family of Birds that is peculiar to it, and that is a Family 
of position so doubtful that some of those who have most closely 
studied it refer it to one or another of well-known Families— 
Paridz or Troglodytide—hboth of which are widely dispersed and 
admittedly contain genera that differ considerably. If by way of 
accommodating these dissentient views we recognize Chama as the 
type of a distinct Family—and in our present state of imperfect 
knowledge no other course seems open—the existence of such a 
Family, Chamzxidz, still seems precarious. Every other Nearctic 
Family is common to the Neotropical Region or to the Palearctic 
area, or to both. Of the Passeres common to the Neotropical Region 
and the Nearctic area 4 Families are admittedly better represented 
in the latter—namely, Wniotiltide by some 13 genera and about 50 
ar 
ee in 
