BORNEAN DRAGONFLIES. 



75 



treat as doubtful. They are Bisparoneura ? i7itegra Selys, and 

 Disparoneura ? obsoleta Selys.] _ 



Further east the genus is replaced by the closely allied Caco- 

 neitra (Alloneura), which in regard to venation is still further 

 specialised. 



Like many other genera which are richly developed m the 

 Malayan region, it appears to be but poorly represented in Java. 

 The Malayan species appear to fall into three groups characterised 

 by the coloration of the males. 



One of these groups, possibly the most primitive, has the males 

 black with yellow markings on the head and thorax. A second 

 is that in which the males show blue markings on a black 

 ground. 



In the third group the males are black, with carmine, brick- 

 red, and orange-coloured markings. 



The females of all these groups appear to be very similar as 

 regards colouring ; they are black, with dull yellow or orange 

 markings. They are, however, remarkable in the possession of 

 various curious developments of the margin of the prothorax. 



The grouping of the species according to the colouring of the 

 male is suggested by Forster*, who regards certain forms with 

 black and red males as races or subspecies of B. verficcdis. I 

 have here extended the limits of his " verticalis section " to include 

 all the black and red Malayan species with no lower sector of the 

 quadrilateral, or with only a trace of it. I think it unnecessary 

 to treat these species as mere subspecies of verticalis ; I believe 

 them to be well characterised and readily recognisable species. 



I propose to group them as follows : — 



A. Head of the male with a red band passing from eye to eye, across the 

 ocelli. 



1. ^. Anterior surface of thorax orange-red, upper lip black, anal 



appendages red-brown. 

 2 . Head black with orange band passing from eye to eye ; prothorax 

 black with lateral orange lines, the posterior margin deeply 

 lobed (echancr6) at its middle. Thorax black, with three 

 yellow bands on either side. JD. dorsalis Selys. Borneo. 



2. (? . Upper lip red ; broad red bands on front of thorax. 



$ . Head black with yellow band from eye to eye ; prothorax black 

 with livid-red lateral lines, its posterior margm carries on 

 either side a strongly cui-ved point. Thorax black, with three 

 yellow or livid-brown lines on either side. 



D. verticalis Selys. Borneo. 



3. $. Small red antehumeral lines on the anterior surface of the 



thorax ; prothorax with a large red spot on either side. 

 $ . Head with complete yellow band from eye to eye ; prothorax' 

 with large red spot on either side. Posterior margm? Small 

 red humeral band on prothorax, and two yellow lateral ones 

 on either side. I>. delta Karsch. Sumatra. 



Java (Forster). 



(None of the males of D. dorsalis that I have examined has any trace of 

 a lower sector of the quadrilateral. In D. verticalis this is at least usually 

 present.) 



* Forster, Fascic. Malay., ZooL pt, iv. Odonata, pt. ii. p. 14, 



