( 252 ) [April, 



7. ENTOMOLOGY. 



{Including the Proceedings of the Entomological Society.) 



Fkom investigations made by M. Felix Plateau* on the mus- 

 cular force of insects, he deduces the following law : — " In the 

 same group of insects, the force varies inversely to the weight, 

 that is to say, that of two insects belonging to the same group, 

 the smaller presents the greatest strength." The Phytophagous 

 families, Donaciidse and Crioceridae, appear to exceed all others 

 in traction-force. The supremacy of these insects he attributes 

 solely to their great muscular force, which is explained partly by 

 the large size of the posterior femora, and partly by their small 

 weight. With regard to the leaping powers of the Orthoptera, 

 he found that (Edipoda grossa, which weighs 0*646 gr., raised 

 a mean weight of 1*064 gr., and (Edipoda parallela, 0*194 gr., 

 raised a mean weight of 0*638 gr. The proportions of their 

 relative force are, therefore, 1*647, and 3*288; another example 

 of the above law, according to which, in the same group of insects, 

 the lightest are comparatively the strongest. As regards flight, 

 M. Plateau finds, also, that the mean forces of insects are still 

 in inverse proportion to the weights; but he obtained no such 

 high results as in the case of traction or pushing. 



Allusion has already been made (ante, p. Ill) to the dis- 

 covery, by Sir John Lubbock, of a new type of centipede. An 

 elaborate paper on the subject has since been read before the Lin- 

 nean Society. The animal is only ^th of an inch in length * has 

 a body composed of ten segments, with only nine pairs of legs, and 

 five-jointed antennae bifid at the extremity and quite unlike those 

 of other Myriapods. It was proposed to be called Pauropus 

 Huxley i. The author, who has found it in great numbers in 

 his kitchen -garden at High Elms, was at first disposed, from 

 its minute size, to regard it as a larva ; but, having examined 

 several hundred specimens, he had come to the conclusion that 

 it was a mature form. In its earliest state it has three pairs 

 of legs, and the number increases at each moult ; two pairs at 

 the first,- but at each of the subsequent moults a single pair 

 only is added. Its systematic position among the Myriapoda is 

 a matter of doubt. Sir John went very minutely into the reasons 

 which induced him to consider that it could not be placed in 

 either of the two great orders of the class, and that it is not 

 only intermediate between the Chilopods and Diplopods, but that 

 it forms a connecting link between the Myriapoda and the other 

 classes of the annulosa. From the view of its being the type of 

 * ' Ann. and Mag. Nat. Hist.,' Feb., 1867. 



