( 566 ) 



(3) individuals of the same species in the same instar, 



(4) sncceeding Lroods, 



(5) specimens of a species from difTerent countries, or 



(6) distinct species. 



The first point has been dealt with above, and some characters which 

 distingnish the adnlt male from the female are also mentioned in the account of 

 the morphology— namely, the tuft at the apex of the fore tibia in all species, and the 

 smaller number of hairs on the abdominal tergites in some— the males, moreover, 

 bearing an organ of copulation directed, as in the bt'd-bug, towards the left side 

 (in Westwood's fig. A of PI. 39 it is erroneously drawn as being directed towards 

 the right side : cf. infra, P. molossus). 



We know nothing about point (4), and as regards (3) and (;")) the number of 

 specimens known is far too small to allow ns to draw any definite conclusion as 

 to the extent of variation in these insects. All we can say is that the few adult 

 individuals we have of the same sex of a species, and from the same place, 

 agree very closely with each other, the number and position of the bristles and 

 the number of spines in the combs only varying within narrow limits. For the 

 study of geographical variation, likewise, a far larger material is required than the 

 collections contain at present. The ? of P. molossus from China and the one from 

 India in the British Museum do not appear to differ. 



Up to 1906 the species of Pohjcti'vidne were dealt with under the one generic 

 name Poli/ctenes Gigl. (1804). At that time four species (or what were thought to 

 be distinct species) were described from the Old World and two from the New. 

 These Kirkaldy (1906) separated into four genera, the distinctions not being taken 

 from actnal specimens, but from the descriptions and figures of former authors, the 

 generic names being flesperoetenes. Poh/ctenes, Eurontenes, and Encteiies. Horvath, 

 in 1910, correctly made Euroctenes a synonym of Poljintenp.s, and ])roposed two new 

 a^xin^—Ctenoplax for a species described by himself, and Si/ncroUis for two species 

 described by Speiser and unknown to Horvath in nature. Syncrotus being pre- 

 occnpied, Horvath in 1911 proposed the na,me Hemisehizus in its stead. In the 

 present paper we add another new genus. 



The number of species being still less than a dozen, it might be considered 

 unnecessary to distribute them over several genera, and it requires, therefore, a 

 few words of explanation why we follow Horvdth's classification, at least to a 

 certain extent, rather than place all the species in one genus. 



Systematics are didactic, the systematist presenting either a description of 

 facts or a reasoned interpretation of facts. This holds good throughout the 

 publications on systematics, with the exception of noniina indescriptn, which on that 

 ground we consider outside the pale of the systematist. Approaching the question 

 of genera from this point of view, it is evident that genera are not mere divisions 

 of a family which are established for the sake of convenience, but have an 

 educational value. Tlie diagnosis of a genus teaches us that the species grouped 

 together therein have certain affinities with each other (which the evolutionist calls 

 evidence of blood-relationship) in contradistinction to the members of other genera. 

 If, therefore, the species of a family are divided strictly according to relationship 

 into a greater number of well-defined genera, the student new to the subject, or the 

 would-be describerof a new species, is at once made acquainted with the characters 

 which are of importance for the recognition of relationship, and at the same time 



