GENUS NEMATUS. 47 



form of the claws, are often of great value in separating 

 species. I have, however, found variations in all these 

 points, and it need scarcely be said that the colora- 

 tion is not always constant, some species varying 

 exceedingly in this respect. 



That the saws afford more or less good specific 

 characters there can, I think, be no doubt. I have 

 had figured as many of them as I could obtain, they 

 being now delineated for the first time. Whether 

 their forms can always be depended upon I cannot say, 

 but I believe they vary within very narrow limits. 



The larvae and habits can most assuredly be depended 

 upon as tests of specific distinction. Indeed, some 

 species can scarcely, if at all, be distinguished in 

 the perfect state, while they are very distinct as 

 larvae. 



The males are much more difficult to distinguish 

 than the females ; they are all very similar in colora- 

 tion, even when the females are very dissimilar. 



In the synoptical tables I have omitted the males 

 entirely, not being able to find sufficiently reliable 

 characters that could be used in synoptical form, and, 

 moreover, I am not practically acquainted with the 

 males of half the British species. In the tables I 

 have had to omit some of the species, as I found 

 it impossible to find differential characters that could 

 be of any use. 



The species are not known beyond the Palsearctic 

 and Nearctic regions.* Kirby (List of Hymen., i, 

 1882) enumerates in all 366 species, whereof 281 are 

 from Europe. No doubt a considerable number of 

 these will ultimately be proved to be varieties or syno- 

 nyms, but as new species are always being discovered, 

 I should not be astonished at there being 400 Euro- 

 pean species. 



They are most abundant in the northern and north- 

 west districts of the Continent. They extend into 



* Except a single species from the North of Mexico at its junction 

 with Arizona. 



