300 THE ENTOMOLOGIST. 



that held by practically all authors since the middle of this 

 century.* 



9. G. argentatus, Schummel. 



= apicalis, Curtis. 



Very closely allied to lacustris. It is not common, but is 

 probably sometimes passed by as the latter species. It is widely 

 distributed over England, and recorded from Scotland and Ire- 

 land. The apical segments of the abdomen are not greatly 

 different from those of lacustris. 



10. G. odontogaster (Zett.). 



Easily recognisable by the two strong ventral teeth in the 

 male, and the transverse seventh segment in the female (figs. 27 

 and 28). 



Generally distributed, though not common. 



Metamorphoses, &c. 



Little detailed information has been published on the meta- 

 morphoses of the Gerridae. Dufourf states that the eggs are 

 deposited one after another, but not touching nor crowded to- 

 gether, in a kind of mucilage fixed upon the leaves of immersed 

 plants. They are elongate, cylindroid, not truncate at either 

 of the extremities. Instead of opening by the unglueing and 

 downfall of a regular operculum — as in the majority of land- 

 bugs — their anterior third splits longitudinally, and by this rent 

 the young nymph leaves. This occurs usually about May or 

 June. The nymphs may be at once separated, at any stage, 

 from the apterous imagines by the frailer frame, shorter abdomen, 

 and by the unisegmentate anterior tarsi. They keep more to the 

 shelter of the banks of the stream or of aquatic plants. The 

 nymphs change into imagines usually about the beginning of 

 August, though — as in most aquatic insects — these periods will 

 bear a very liberal interpretation. Like the imagines, they feed 

 on minute dead or dying flies, &c, that have fallen into the 

 water, and are sprawling helpless on the surface. 



* I have dealt with the synonymy of lacustris in this manner because 

 Renter cites the modern acceptation, indorsed by him, as an exception to 

 his rule. 



f 1833, Mem. div. savans Acad. Sci. France, iv. p. 347. 

 (To be continued.) 



