IBS The ^\\Tuim itistoi'cY ntxir^. 



hesitated to put the discovery upon record. Moreover the fact has 

 been conlirined by the observations of others. Polynema natans, the 

 insect which exhibited so unlooked-for a phenomenon, was found " in 

 a basin of pond-water," together with another member of the same 

 order, of which no truly aquatic species had previously been noted. 

 This second form is referred to a new genus, Presfwichia. Its 

 wings closely resemble those of Polynema, though it holds these 

 organs " motionless, and uses its legs as oars." Both these insects 

 afford the text for a number of suggestive considerations on the 

 varying reliitions of animals to the elem^ents in which they live, 

 which we forbear to abridge, referring our readers to the paper itself. 

 No branch of natural history is more interesting or less technical 

 than this, yet how few are the methodised contributions made to its 

 annals by those who have leisure and ability to become constant 

 observers. But the mind sees what it brings mth it the means of 

 seeing. Mr. Lubbock's opportunities for the quiet contemplation of 

 living organisms in their native habitats are well known to be few 

 and far between, and we rejoice, therefore, at his success, — a success, 

 however, at which eoc-professo entomologists should blush. They 

 have described about 12,000 Hymenopterous species, of which one- 

 fourth are British, transfixing with pins some millions of individuals 

 and detailing, with painful minuteness, their most obscure and tran- 

 sient characters ; yet, in spite of all this trouble, they have allowed 

 the most curious member of the entire group to escape them. 



Mr, Lubbock contributes a third paper, ' On the development of 

 Chheon {Ephemera) dimidiatum.'' Its main object is to show that the 

 terms by which we seek to define the metamorphoses of insects need 

 revision, if we wouldhenceforthemploy them Avith scientific accuracy. 

 AVe are accustomed to resolve the life of insects into three or four de- 

 finite stages, but facts prove that in several insects, " there is no such 

 " well-marked, threefold division ; and that, in the Ephemeridfe at 

 "least, the young insect gradually attains its perfect condition 

 " through a series of more than twenty moultings, each accompanied 

 " by a slight change of form." In support of this proposition Mr. 

 Lubbock describes seventeen successive states in the development of 

 Chloeon. These details are introduced by some striking prefatory 

 remarks on the metamorphoses of insects in general, their causes, 

 and the external conditions to which they are adapted, and which, 

 in turn, modify their occurrence. 



lapyx is a new genus of Thysanura, allied to Campodea^ "West- 



