( H ) 



182 species ; the volume now under consideration including part 

 of the Pemphigmce, the Chermesina;, and the Rhizobiince. There 

 is also a chapter on Aphides in their economical relations to 

 Ants ; elaborate treatises on the reproduction of Aphides, and on 

 their biology and morphology; notes on the antiquity of the 

 Hemiptera, particularly with regard to Aphides as represented in 

 the sedimentary rocks and in amber ; observations on the natural 

 and artificial checks to the increase of the creatures, on the 

 mounting of specimens for the microscope and preservation for 

 the museum ; and lastly a bibliographical list of authors who 

 have treated of the life-history or anatomy of the group. 



According to M. Lichtenstein, the evolution of plant-lice is 

 entirely different from the common metamorphosis of other 

 insects, and may be compared to the growth of a plant. The 

 egg does not produce a male or female insect, but an agamous 

 form, which by a sort of budding process reproduces numbers of 

 individuals which are able to continue this budding reproduction 

 for a more or less prolonged period, until there arrives a time at 

 which the produce of these gemmations no longer consists of 

 agamic, but of sexuate insects, male and female, which last lays 

 the fecundated egg and gives origin to a new series of beings. 

 M. Lichtenstein proposes for the agamous forms the name of 

 Pseudogyna; and considering them to be only transitory or 

 larval forms, he calls the four stages preceding the appearance 

 of the sexed insects pseudogyna fundatrix, migrans, gemmans, and 

 pupifera—fundatrix, the foundress of the colony, the first form 

 issuing from the fecundated egg, the form which generally causes 

 the galls in those species which produce galls ; migrans r the 

 second or winged form which flies away from its birthplace ; 

 gemmans, the third form of budding reproduction, without access 

 of the male ; and pupifera, the fourth form, which produces the 

 sexed insects. 



M. Lichtenstein's terms are not happily chosen ; it is startling 

 enough to talk of the winged migrant form as a larva, but it is 

 confusing, or worse, to speak of another form of pseudogyne as 

 carrying a pupa inside her, and describe her as laying pupae, 

 not eggs. Yet this is M. Lichtenstein's view ; for he avows 

 that by the word "pupifera" he wished to establish that it is not 

 an egg, but a true pupa or chrysalis, that is produced by his 

 fourth form — a view which is controverted by Balbiani, Eiley, 



