ORTHOPTEKA. 153 



it must have had a disadvantage in checking cross-fertiliKation. The 

 chances of a male safely arriving from a distant locality was small, 

 and involved great losses to the species, whilst local males would 

 involve inbreeding, therefore any very isolated colony would be advan- 

 taged by doing without males. That this advantage was not one 

 obtainable under all circumstances, but only under some, such as, 

 especially, isolation of a colony, is proved by the fact of forms with 

 males being still rather more numerous. That the parthenogenesis of 

 Ajihides should have gone to such a fuller development than in Liiffia, 

 results, doubtless, from its greater duration, hemiptera being so much 

 older than lepidoptora. Aphides also having many generations in 

 a season, are really 20 or 50 times older than their greater antiquity 

 involves. In ( 'ynipx, parthenogenesis has resulted from different 

 forces, or from forces that have acted in a different way. Apterous- 

 ness is a small, or evanescent, element in association with it ; it 

 affects some of the parthenogenetic alternative generations, but I do 

 not recollect a case of it occurring in any continuously parthenogenetic 

 species. 



There is one other point in connection with these parthenogenetic 

 Luftias and Solenobias that goes a long way to show that they are a 

 comparatively modern development, and have much interest from 

 several other points of view to the biologist and field naturalist, that 

 is, the fact that each parthenogenetic race or species appears to be 

 closely related to an ordinary form, so closely that the question is, or 

 always can be, raised, as to whether it is truly a distinct species. Now 

 in the case of our Liijfia fcrchaidtrUa, an adult case, or an imago, can 

 always be distinguislied from one of L. lajnilella simply and in itself, 

 without any history of the specimens or outside circumstances. I say 

 can be, because I should not like to say that I could do so, say, next 

 year, without again examining a number of specimens and refreshing 

 my knowledge of them. Nevertheless, I have suggested already some 

 grounds, such as the existence of L. iiuvn/icUa, and occasionally " call- 

 ing " $ s of L. feirhaidtella, that show that, perchance, f,. fcrr'hanUcUa 

 is not yet fully distinct as a species from L. lapidclla. When we come 

 to Sohniiibia lic/iciidla we come to a species that, so far as we know, 

 has no intermediate forms towards .S'. inconsjiicnclla. but also one that is, 

 in its case, larva, imago, &c., quite indistinguishable from that 

 species. Solfuohia trujuctydla is regarded by those who have studied 

 it in the field as being a species like N. iucoitspiruella with male and 

 female, but in some localities getting on with a very trifling allow- 

 ance of males, and in others never having any. The parthenogenetic 

 form of S. triquetrella has not received a separate name, and if the 

 facts be as I have outlined them, ought not to have one. I found a 

 parthenogenetic Solcnohia last year at Luino that is, I think, related 

 to N. (iathvella, but I am not familiar with either .S'. clatltrdla or N. 

 triiiiii'trclla sufficiently to care to decide whether it is so or not. 



f Til he concluded.) 



@RTHOPTERA. 



A LIST OF Scottish Orthoptera. — In the Aiiiuih of S,-i,ttis/i Xatiiral 

 Hititori^, January, 1901, Mr. W. Evans contributes a few notes on 

 Scottish orthoptera. A considerable number of localities are given 



