1906. I 207 



For the nationality of the other twelve T can personally vouch. Of 

 these species about half can as a rule be distinguished pretty easily, 

 ])rovided that the specimens examined are in tolerable condition ; 

 but the remainder belong to a group which 1 must confess I find ex- 

 tremely puzzling — viz., that which includes the species commonly 

 known as cnprece and its allies, and which is characterized by the very 

 long 8th dorsal segment in the ^ ^ , and the dilated tempera in the 

 $ ? . In tabulating this group I have thought it best to reproduce, 

 as exactly as possible, the dichotomies employed by Konow in dis- 

 tinguishing and arranging its species. In dealing with the remainder 

 of the genus, however, I have allowed myself more freedom ; and 

 have preferred to found my divisions on such characters chiefly, as I 

 personally find it easiest to recognise in actual specimens. 



In several species of Fachynematus (just as in Pteronus, &c.) the 

 ground-colour (especially of the ? ? ) changes after death from green 

 to various more or less impure and blended tints of red, brown, yellow, 

 and even white. In others it is permanently (i. e., before and after 

 death) and dejinitely fulvous. kSometimes it is easy to say at a glance 

 to which of these sections a specimen should be referred. And with 

 long practice the eye gains a sort of experience, which makes such 

 discrimination easy ; but there are cases which to a novice would 

 present insoluble problems. Another difficulty, which is perhaps a 

 still more fi-equent source of errors, is the often very great similarity 

 — as far as colour goes — between certain pale or discoloured PacJiy- 

 nemati and various species belonging to other genera. Errors from 

 this cause may, however, be absolutely avoided by making it a rule 

 never to attempt the naming of such insects without, first of all, ex- 

 examining (I) the clypeus (holding the insect for this purpose upside 

 down !), and (2) the claw^s. If the state of a specimen makes such 

 examination impossible, it is useless to waste time over it ; and the 

 sooner it is thrown away the better ! 



SYNOPTIC TABLE OF BRITISH PACRYNEMATUS, spp. 



1. Last dorsal segment of <? abdomen much produced at apex (making its entire 



length at least twice that of the preceding segment !). Head of ? widened, 



or at least not narrowed, behind the eyes 2. 



— Last dorsal segment of S abdomen hardly longer than the preceding segment : 

 its apical process short. Head of ? narrowed behind the eyes 8. 



2. Wings slightly clouded with brown, clearer at apex. J with head thorax and 



propodeum black, the rest of the abdomen, the tegulse, and the legs reddish- 

 yellow : the ? coloured very like several other species of the group, brownish- 

 orange, with the ocellar region, the meso- and metanotum, the basal part at 



