Notices of New Books. 4143 



literature are more or less injured by the shortcomings of any one of 

 their number. 



From these observations, imperatively called for but penned with 

 great reluctance, we turn with pleasure to the work itself, which is 

 admirably executed, and a long-desired addition to our Natural- His- 

 tory literature. This last part, containing the Introduction, is the 

 most valuable of all, and we particularly commend to the close and 

 studious attention of our readers the following most interesting pas- 

 sage on the metamorphosis of the Crustacea. 



" One of the most marked characters by which this class was long 

 considered as distinguished from that of insects, was the supposed 

 absence of any such change of form, during the progress of develop- 

 ment after exclusion from the egg, as is ordinarily understood by the 

 term metamorphosis : and Dr. Leach, in his definition of the class, 

 formally adopts this character, which has been repeatedly recognised 

 by others. 



" It was in the year 1823, that Mr. Vaughan Thompson, whose 

 name is now identified with the discovery, following up an observa- 

 tion made by Slabber, a Dutch naturalist, as long ago as 1768, and 

 published ten years afterwards, established the remarkable fact that 

 those anomalous forms which constituted the genus Zoea of Bosc, are 

 nothing more than the early or larva condition of the higher Crusta- 

 cea. It will readily be imagined that no small excitement was pro- 

 duced in the scientific world by the announcement of a discovery 

 which, followed up, as it afterwards was, with equal intelligence and 

 perseverance, and with corresponding success, may claim for its au- 

 thor a place amongst the few observers who, from a single phenome- 

 non, have been led to the establishment of generalisations and laws of 

 the highest importance. 



" Notwithstanding, however, the credit is due to Mr. Thompson of 

 having carried out the suggestion to its full development, it was un- 

 doubtedly to the Dutch naturalist that he was indebted for the ascer- 

 tained fact that the anomalous creatures on which Bosc afterwards 

 founded his genus Zoea pass by metamorphosis into a different and a 

 higher form. 



" Before I proceed with the further history of this discovery, I think 

 it right to show the grounds of Slabber's claim, which had been wholly 

 overlooked as to its results, and which, in consequence of an error 

 arising from deficient information, Mr. Thompson himself, in the first 

 place, much depreciated, without, as far as I am aware, having after- 

 wards taken any opportunity of correcting the misapprehension. It 



