I92I-] F. F. Laidlaw ; Indian Drai^onflies. 8i 



low, carried on to the apex of 3 laterally. Legs black-brown. 

 Base of femora brown. Wings with saffron tinge at base, extend- 

 ing nearly to the arculus. Length of abdomen 44 mm., of hinder- 

 wing 41 mm., of pterostigraa 2 mm. Breadth of hinder-wing 

 I2*5 mm. 



The apex of the dentigerous plate of this specimen is pro- 

 duced into two stout processes, which are directed almost directly 

 backwards. 



The plate has been somewhat compressed in mounting the 

 specimen, and the text-fig. accordingly shows a slightly distorted 

 view of the apex of the plate. 



Periaeschna magdalenae, Martin. 



Pen'aesiiiiid imigdahiiac, .Martin, Cat. Cu/I. Selvs Aeschninm'. p. 157, tit;. 

 I S7r pi. vi, fig. 22. 



I cr" I 5 . Tura, Garo Hills, Assam. 7975/H i. 



These specimens agree closely with the tj'pe specimens des- 

 cribed by Martin from Tonkin. Dr. Ris tells me that he possesses 

 specimens of what is probably a distinct species from S. China. 

 I have already noted that I believe Caliaeschna laidlawi, Forster 

 IS to be referred to this genus. 



Periaeschna confronts us with the problem of the independent 

 development of similar structures. It has the venation of the 

 Brachytron series combined with a dentigerous plate scarcely 

 distinguishable from that of Gynacantha. 



Group AESCHNA. 



Three series of genera are referred to this tribe, each series 

 culminating in one of the three dominant genera of the sub- 

 family, Aeschna, A nox and Gvnacantha. The tribe is characterized 

 by the curving of Rshl and Mspl so that they are concave to Rs 

 and M ^ respectively, and separated from them by at least three 

 rows of cells. Each series is represented in India, Aeschna. is 

 mainlj' a temperate genus and has but few representatives and 

 those rather aberrant. Anax perhaps the most successful form of 

 the subfamily is remarkable rather for the wide range and indivi- 

 dual abundance than for the number of its species, whilst Gyna- 

 cantha, a very specialized holotropical genus, includes a number of 

 crepuscular or shade-loving insects, which are often caught at 

 hghts. In addition certain more primitive genera of the tribe 

 are found in the Oriental Region, but so far as I know none have 

 hitherto been recorded for the Indian Empire. Of these genera, 

 which are mainly Malayan in A\s^:nh\it\on , Amphiaeschna seems 

 to me to be a primitive member of the Aeschna series, whilst 

 Heliaeschna is similarly related to GynacantJia. Heliaeschna is 

 also closely related, possibh^ even ancestral to Telracanthagyna , a 

 genus which contains the most nearly gigantic of living dragon- 

 flies. 



