372 Analytical Notices of Books. 
which was found a litter of the young of Mus minutus, Pall. a species 
regarded by the authour as identical with the Mus messorius and Harvest- 
mouse of Shaw and Pennant. The most artificial of these nests, which 
in skilfulness of construction was fully equal to that of most birds, was 
suspended from the summit of three straws of the common reed (Arundo 
Phragmites, L.) and was entirely composed of the panicles and leaves 
of the plants, slit longitudinally and intricately plaited and matted to- 
gether. Its internal cavity was smal] and round, and accessible only by 
a narrow lateral opening. From the peculiarity of its structure, there 
can be little doubt that this curious nest was fabricated by the animal itself, 
and not merely adopted by it; and this conclusion is confirmed by the 
description of a similar nest, also containing young, found in the neigh- 
bourhood of Berlin, by a pupil of Professor Lichtenstein, through whom 
the account of this discovery, inserted at the end of the volume, was 
communicated to the authour. The value of the paper is much enhanced 
by the general observations with which it commences on the stimulus by 
which Birds and Quadrupeds are impelled to construct their habitations; 
and by the comparison which follows of the means possessed by each 
class as a whole, as well as by the individual species composing it, for 
carrying this impulse into effect. 
The “Versuch einer Natiirlichen Eintheilung der Vogel, von Dr. 
« F. A, Ritgen,” isa specimen of the trichotomous system, applied to 
the classification of birds. This arrangement professes to be founded on 
the modifications of the pelvis, coincident with those of its locomotive 
appendages, and with corresponding variations in the functions of these 
parts, so important in determining stations and habits. No details, 
however, are given of the structural characters employed; those which 
depend on the pelvis being expressly reserved for another opportunity. 
The subdivisions appear to be the result of a comparison of structure and 
habits: thus for instance the primary distribution into three series, as they 
are termed, is effected either in conformity with habits, according as the 
abode of the birds is more peculiarly the water, the dry land, or the 
marshes; or with reference to structure, according as the hinder limbs 
serve more the purposes of fins, of hands, or of feet. The following 
tabular view will give an idea of the manner in which the authour follows 
