580 Analj/tical Notices of Books. 



The extract from a memoir of M. Blot on the properties of the 

 Insects found in the vicinity of Caen, contains many curious, and 

 some new, facts, relative to the damage occasioned by these 

 minute yet powerful agents in the economy of nature. In some 

 points the remarks of the authour would have been more valuable 

 had he been possessed of more extensive information. Thus he 

 regrets that Ants have never yet been looked to as furnishing an 

 instrument in the hands of the Physician , surely M. Blot cannot 

 have failed to have met with, in common with almost every reader, 

 the Aqua Magnanimitatis of the older writers on medicine. This is 

 not however the place to enter into any details on the subject of 

 the present article, and we shall therefore pass on to the succeed- 

 ing one, a memoir by M. E. Deslonchamps on the shells of the 

 genus Gervillia. 



Iq the character of this genus as given by M. Defrance, (to 

 whom we are indebted for the first notice of it, which he deduced 

 from the cast of a single species, G. solenoides,) M. Deslonchamps 

 proposes several modifications, which enable it to receive four 

 other shells which appear to be intimately connected with it. 

 These are the G. pemoides, (Pernaaviculoides, Sow. Min. Conch, 

 t. 66,) G. siliqua, G. monotis, and G. costatula, all of which are 

 figured and described. In opposition to the opinion of M. De- 

 france, the author of this memoir conceives that Gervillia has no 

 opening for the passage of a Byssus. Should this prove to be the 

 case, which we are rather inclined to doubt, it will effectually 

 separate the shells of this, from those of the other genera of 

 Malleaceae. Their nearest affinity is with those of Perna, from 

 which they may at once be distinguished by possessing an appa- 

 rently inner additional hinge, formed of several oblique teeth 

 variously disposed according to the species. 



The observations by M. Gaillon on the cause of the colouring of 

 Oysters and on the animalcula by which they are nourished, are a 

 continuation of the enquiries previously instituted by that gentle- 

 man, some of the results of which had already appeared. Ac- 

 cording to his observations, several of the Infusoria possess the 

 power of uniting themselves to form filaments, which have been 

 frequently confounded with Byssi and Confervae, and in this state 



