128 MODERN CLASSIFICATION OF INSECTS. 



MacLeay observes, by their affinity to European insects, how much 

 fewer typical forms there are of aquatic than terrestrial insects. Al- 

 though few in number, however, the species are very widely dis- 

 tributed, having been received from all quarters of the globe. Dejean, 

 in his new catalogue, gives 101 species, of which seventy-nine are 

 extra-European ; whilst Mr. Stephens gives descriptions of about forty 

 British species. Dr. Leach in the Zoological Miscellany, and M. 

 Solier in the Annales de la Societe Entomol. de France, have published 

 distributions of this family, — the various genera now adopted having 

 been chiefly proposed by these two authors. 



The species of the British genus Limnebius are of a very small 

 size, none exceeding one eighth of an inch in length. In their habits, 

 and partially in their structure, they approach the Helophoridae. This 

 genus is one of the best marked in the family, and yet appears to be 

 unknown to recent French authors, who, neglecting Leach's characters, 

 give the aberrant species of Hydrobius as its examples, which, from 

 the differences which they exhibit, I have adopted as distinct groups, 

 as introduced into my Generic Synopsis, p. 10. The genus Hydrophilus 

 comprises the gigantic H. piceus, a species not rare in the neigh- 

 bourhood of London, and which is an inch and a half long, and many 

 large exotic species, some of which, forming Solier's genus Stethoxus, 

 have the anterior male tarsi simple. 



The exotic genus Volvulus JBruUe consists of a single species (V. 

 inflatus), which I have received from M. Desjardins of the Island of 

 Mauritius, remarkable for its inflated aiid very compressed form. That 

 of Globaria^ as the name implies, is very globose, and contractile into 

 a ball. 



The family SpHiERiDiiDiE* Leach, consists of a small group of 

 species remarkable for their close relationship with some of the Hydro- 



* BiBLioGR. Refer, to the Sph^eridiid^. 



Leach. Zool. Misc. vol. iii. 



Stephens. 111. vol. ii. 



Audovin and Brnlle, loc. cit. supra. 



Say, in Joiirn. Acad. Sc. Philadelpli. vol. iii. 



Erichson. Kafer Brandenburg. 



And the general works of Gyllenhall, Eliger, Geittmr, Herbst, §-c. 



