ig22.] F. F. Laidlaw : Indian Dragonflies. 375 



Five oriental genera can be distinguished. They may be very 

 briefly separated as follows : — 



A. Large insects (h.\v.>36 mm.) ; ninth abdo- 

 minal segment much longer than eighth ... M/Jcrogom pints Selys. 



B. Size moderate or small (h.w. usually less than 

 36 mm) : ninth abdominal segment smaller than 

 eighth. > 



A Basal antenodal nervure of 2nd series present heptogomphus Selys. 

 //. Basal antenodal nervure of 2nd scries absent 

 a. Sectors of arculus approximated shortly 

 after their origin. 



1. Size moderate (h.w. 25 mm. or more) ; 

 outer side of triangles straight ; upper 



anal appendages of male lyrate ... Heliogomplnts, ge\\. nov. 



_>. Size small (h.w. about 20 mm.) ; outer 

 side of triangle broken ; upper anal ap- 

 pendages of male chelate ... ... Micvogomph us Selys. 



/>. Sectors of arculus not approximated after 



their origin ... ... ... Perissogomplius, gen. nov. 



The unsymmetrical character of the forking of Mj_ 2 and 

 M s (which Williamson, doubtlessly the result of a lapsus calami, 

 writes as M,_ :! and MJ is much more obvious in Lcplogomphus , 

 Heliogomphus and Microgomphus, than in Macrogomphus and in 

 Perissogomphus. As to the specialization of cross-nerves between 

 Mi_ 3 and M 4) in all genera of the series Gomphus that I have 

 examined, or of which I have seen photographs, the forking of 

 M,_ 2 and M 3 is preceded in the hinder- wing by a single cross- 

 nerve only. In Perrissogomphus, least typical of oriental Epi- 

 gomphines, this forking usually occurs at the level of the third 

 cross-nerve, occasionally distal to it. 



The genera of this series are confined so far as is known to 

 the Oriental and Neotropical Regions. 



Genus Macrogomphus Selys. 



Genotype : Macrogomphus robustus Selys. 

 Species examined: M. annulatus Selys; M. robustus 

 Selys; M. montanus Se^-s ; M. decemlineatus Selys; 

 M. quadratics Selys. ^ 



Large insects (h.w. about 40 mm., abdomen still longer) easily 

 recognized by the curious lengthening of the ninth segment of the 

 abdomen in both sexes. Pterostigma unbraced. Forking of M[_ 2 

 and M 3 not markedly asymmetrical, more so in fore than in 

 hinder-wing. Cubital space usually with two cross-nerves. Upper 

 anal appendages of males chelate (much as in Microgomphus). 



The lengthening of the ninth segment of the abdomen is 

 diagnostic and at once distinguishes a Macrogomphus from any 

 known oriental genus. The segment is roughly twice as long as 

 the eighth. 



Macrogomphus robustus Selys. 



2C ? ( ? . Assam. 



I 9 • " Sibs. - '=Sibsagar ( 6331 1). Specimen identified by dc Selys. 



