190 
ZOOLOGICAL LITERATURE. 
Avill operate more rapidly and over wider spaces ; but both are 
liable to be limited by natural geographical boundaries^ such as 
broad rivers^ inoimtain-chains, and arms of the sea, ol course 
in varying degrees, according to the facilities for diflusiou 
possessed by the different organisms. In reality the author's 
arguments lead to the conclusion that isolation is a necessity for 
the production of new forms by transmutation, and that it is 
by means of migration that this is brought about, which will 
probably be admitted in the majority of cases by most Dar- 
winians ; but the examples cited by him will be found very in- 
teresting and instructive. 
B. Works in ‘proyress. 
L'Abeille. Memoires d'Entoinologie par M. S. A. dc Marscul, 
avec la collaboration de plusieurs membres distingues de la 
SocieteEntomologique de France. Tome v. livr. 1-5 : 1868. 
Five parts of this periodical were actually published in 1868 ; 
the sixth part, completing the volume for last year, appeared on 
the 35th February, 1869. The contents of these parts relate 
exclusively to Coleoptera. 
Packard, A. S. A Guide to the Study of Insects, and a Trea- 
tise on those injurious and beneficial to Crops. Parts I. & 
II, 8vo, pp. 128. Salem, 1868. 
In this work Dr. Packard aims at giving the outlines of the 
natural history of insects, in a simple popular form, with as 
little use as possible of technical terms. The Recorder has seen 
only two parts of it, which were kindly sent to him by the author : 
these were published in June and July of last year; and as the 
whole is stated to consist of 8 or 10 such parts, the work is 
probably by this time completed. The portion before the Re- 
corder, however, is quite sufficient to enable him to speak of the 
general character of the work, which, as might be expected 
from the deservedly high reputation of its author, is of admi- 
rable quality. Dr. Packard commences with a general account 
of the anatomy and physiology of insects, which is far superior 
to anything of an elementary nature that we possess; he then 
briefly treats of the geographical and geological distribution of 
insects, of their diseases and deformities, and of the methods of 
collecting and preserving them. A list of some of the prin- 
cipal works in various departments of entomology is then given ; 
and this is followed by the systematic part of the work, of 
Avhich only a small portion, including the higher .forms of Ily- 
menoptera, is given in the second part. The author regards 
all the Arthropoda, with the exception of tlie Crustacea, as 
forming ‘^Ghe class of insects," which he divides into the three 
orders Hexapoda, Arachnulay and Myriapoda. The Hexapoda, 
or true insects, are regarded by the author as forming two sc- 
