eful account of the temperate
parts of South America interested me much, and all the more from knowing
something of the country. I like also much the general remarks towards
the end of the volume on the land molluscs. Now for a few criticisms.

Page 122. (392/1. The pages refer to Volume II. of Wallace's
"Geographical Distribution.")--I am surprised at your saying that
"during the whole Tertiary period North America was zoologically far
more strongly contrasted with South America than it is now." But we know
hardly anything of the latter except during the Pliocene period; and
then the mastodon, horse, several great edentata, etc., etc., were
common to the north and south. If you are right, I erred greatly in my
"Journal," where I insisted on the former close connection between the
two.

Page 252 and elsewhere.--I agree thoroughly with the general principle
that a great area with many competing forms is necessary for much and
high development; but do you not extend this principle too far--I should
say much too far, considering how often several species of the same
genus have been developed on very small islands?

Page 265.--You say that the Sittidae extend to Madagascar, but there
is no number in the tabular heading. [The number (4) was erroneously
omitted.--A.R.W.]

Page 359.--Rhinochetus is entered in the tabular heading under No. 3
of the neotropical subregions. [An error: should have been the
Australian.--A.R.W.]

Reviewers think it necessary to find some fault; and if I were to
review you, the sole point which I should blame is your not giving very
numerous references. These would save whoever follows you great
labour. Occasionally I wished myself to know the authority for certain
statements, and whether you or somebody else had originated certain
subordinate views. Take the case of a man who had collected largely on
some island, for instance St. Helena, and who wished to work out the
geographical relations of his collections: he would, I think, feel very
blank at not finding in your work precise references to all that had
been written on St. Helena. I hope you will not think me a confoundedly
disagreeable fellow.

I may mention a capital essay which I received a few months ago
from Axel Blytt (392/2. Axel Blytt, "Essay on the Immigration of
the Norwegian Flora." Christiania, 1876. See Letter 387.) on the
distribution of the plants of Scandinavia; showing the high probability
of there having been secular per