. Transactions of the Entomological Society of London. an can undertakethe function of the lost one. At any rate, this seems to bethe explanation of the development of such false combs inspecies which we must assume from all we know of themand their allies to have possessed originally normal combson the segments now provided with false ones. Bat-parasites provide us further with an interesting caseof the evolution on parallel fines which occurs in these differ-ent groups of Epizoic insects. The legs of Polyctenidae haveso-called pseudojoints varying in number according to in-dividuals, species
. Transactions of the Entomological Society of London. an can undertakethe function of the lost one. At any rate, this seems to bethe explanation of the development of such false combs inspecies which we must assume from all we know of themand their allies to have possessed originally normal combson the segments now provided with false ones. Bat-parasites provide us further with an interesting caseof the evolution on parallel fines which occurs in these differ-ent groups of Epizoic insects. The legs of Polyctenidae haveso-called pseudojoints varying in number according to in-dividuals, species or genera. The pseudojoints are pale ringswhere the chitin is less thick and hard, rendering thelegs more flexible. Similar pseudojoints are found in Nycteri-biidae, and in the bat-infesting genus of bed-bugs, Loxaspis(text-figs. 26-30). The bat-fleas, however, although long-legged, have no pseudojoints. The occurrence of such acurious structure in parasites living on the same family ofhosts, or even on the same individual, is certainly not ( clvi ). Fig. 26. Leg of Listropodia blasii Kolen. (1856).,, 27. ,, Colpocephalum truncatum Piag. (18S0).,, 28. ,, Hesperoctenes.„ 29. „ Adroctenes horvatki Jord. (1910).,, 30. ,, Loxaspis mirandus Roths. (1912). accidental, but must be assumed to be due to the similarityof surroundings. From the various examples of resemblances I have men-tioned, it is evident that the medium in which a species existsexercises a most powerful influence on its evolution. If thatis so in the case of Epizoic insects, we are not far wrong inassuming that the similarities, often slight in themselves,which sympatric insects (i. e. insects living in the samedistrict) exhibit, are due in the first instance to similarity inthe surrounding primary conditions of life. It only remains for me to express my thanks to theOfficers and Council for the assistance which they have givenme during my term of office, and especially to the Vice-Presidents, on whom, through u
Size: 1717px × 1454px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookauthorr, bookcentury1800, booksubjectentomology, bookyear1836
