BihliograpUcal Notices. 133 



of the multitude of living beings called " In/iisoria" — a term em- 

 plo3?ed by Ehrenberg to include a wide range of animal and vegetable 

 life, but now restricted in a great measure, and specially confined, by 

 Dr. Stein and MM. Claparede and Lachmann, to denote the ciliated 

 members of the group o{ Protozoa ; and he adds that, as the former 

 editions of the work have included the Rotatoria, together with a 

 history of the Bucillaria, Phytozoa, and Protozoa, under the name 

 of Polygastrica, he has felt it incumbent on him to retain these 

 groups, although the researches of late years have so extended our 

 acquaintance with them, that much difficulty has been experienced 

 in the attempt to comprise the whole in a single volume, so necessary 

 for a practical manual. 



In the first portion of the work is comprised an immense mass of 

 valuable information regarding the general history of the minute 

 forms of the animal and vegetable worlds, derived from the pub- 

 lished researches of almost every British and Continental authority. 

 "With reference to this section of the volume before us, we can safely 

 say we have rarely met with a more comprehensive and ably arranged 

 " rhume." 



The second portion, which enters into special descriptions of the 

 separate famihes, genera, and species, furnishes us, for the first time 

 m a collected shape, with notices of a large number of new or very 

 imperfectly known forms, hitherto dealt with only in monographs 

 for the most part inaccessible to the student. And lastly, Mr. 

 Pritchard has enhanced the usefulness of his work by the addition 

 of no less than twenty- one admirably executed plates containing 

 figures of all the most novel and important accessions in each depart- 

 ment treated of. 



We have no hesitation, therefore, in recommending the ' History 

 of the Infusoria ' to all who are anxious to possess a really standard 

 work of reference on the minute forms of animal and vegetable life. 



Cyhele Britannica ; or, British Plants and their Geographical Re- 

 lations. By Hewett CoTTRELL Watson. Vol. IV. Longman 

 & Co., 1859. 



[Second notice.] 



At the beginning of the tenth chapter it is urged that no comparisons 

 should be attempted as to the number of species found in different 

 countries, unless due care be taken that the areas contrasted be 

 themselves equal. Other conditions being the same, the smaller the 

 district, the more numerous, relatively, is the flora found upon it, 

 but the less similar the plants, because they represent more orders 

 and genera in proportion to the absolute number of species : this 

 shows that original centres of creation are more likely for species, 

 than for orders and genera (p. 399). 



It is well known that no two countries, unless very small and 

 adjacent tracts, present the same flora. The difi^erences between the 

 two are more in species than in genera, more 'mgenerai\xdi.\\\n orders. 



