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 intrieately plaited and matted to- 

 gether. Its internal cavity was small 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 Berhn, 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 Vdgel, von Dr. 

 " F. A. Ritgen," is a 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, 

 howeyer, 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 



