1922.] 



F. F. Laidi.aw : Indian Dragonflies. 



377 



Macrogomphus montanus Selys. 



ic 7 . Calcutta (5255/20). 19. No locality (5921/13). Both in poor 

 condition. The male identified and labelled by de Selys. 



Readily distinguished from the preceding species by its gene- 

 rally lighter colouration, which appears to me in some respects also 

 to be more primitive. On the 

 synthorax the juxta-humeral 

 stripes are conspicuous, though 

 incomplete below. The mete- 

 pisternite is yellow, outlined 

 by black lines along the lateral 

 sutures. The basal yellow rings 

 on segments 2-8 of the abdo- 

 men occupy about the basal 

 third of the segment. The 

 abdomen of the male specimen 

 is missing, that of the female 

 lacks segments 7-10. 



Length of hinder-wing in c? 



t"iG. 2. — Colour-pattern of synthorax of 

 Macrogomplnis niovtanus Selys. 



38 mm., in 41 mm. 



In addition to these Indian species of Macrogomphus three 

 other species apparently closely related to one another occur in 

 Malaya. These species are M. parallelogramma Burm., M. albar- 

 dac Selys, and M. decemlineatus Selys. 



Of these species M. parallelogramma has no trace of the juxta- 

 humeral stripe on the synthorax. The metepisternite is black, but 

 with a narrow vestige of yellow banding in its middle. It is 

 recorded from Java and Sumatra. M. albardae is very closely re- 

 lated (possibly only a local race) and differs from M . parallelogramma 

 in having the metepisternite entirely black. M. decemlineatus has 

 the dorsal stripes of the synthorax very narrow, juxta-humeral 

 stripes present, complete but very narrow, mesepisternite yellow, 

 but with black bands on the lateral sutures as broad as the yellow. 

 Metepimerite yellow with well-marked black posterior margin. 



Lastly, three Malayan species form a distinct section of the 

 genus. This is characterized by the large size of its members, 

 the well-marked curving and complexity of the sectors of the 

 wings, and the specialized colouring of the synthorax. The species 

 forming this section are M. quadratus Selys, from Borneo and the 

 Malay Peninsula, M. thoracicus McLach., from Sumatra and also 

 from the Malay Peninsula, and M. abnormis Selys, probably 

 from Borneo. In them the dorsum of the synthorax is black with 

 a large squarish yellow spot occup}dug about its anterior half. 

 The way in which the species of the first section of the genus 

 ' ring the changes ' in the colour-pattern of the synthorax is 

 very remarkable. It is parallelled in other genera of Oomphinae, 

 but it seems to me that in other groups of Anisoptera at any rate 

 the specific differences are of some other character. Here they 



