IQ22.] F. F. Laidlaw : Indian Diagonfties. 389 



In the male the last five segments of the abdomen are entirely 

 black. The seventh segment shows a peculiarity that I have not 

 seen remarked on. A little beyond the middle of the segment the 

 ventral border of the tergite is produced on either side to form 

 a small tubercle-like process armed with stout hook-like spines 

 directed backward. The ventral margins of the tergite of the 

 eighth segment carry a series of spines, about the middle of the 

 segment, rather larger than is usual in that position, and the sternite 

 of that segment carries, close after its base, a small blunt projec- 

 tion. The significance of these structures is unknown to me. 



The anal appendages of the male resemble rather closely 

 those of D. cuniculus Ris, a Japanese species. 



Of the species 

 referred to the genus, 

 D. nanus Selys would 

 appear to have a 

 doubtful right to the 

 position. As Ris has' 

 pointed out the anal 

 appendages of the 



male are quite unlike l ' ,G " lo " -Y^f ab * wnen of Davidiusdavidi assa- 



^ mensts l.aidlaw, o. .v. process of edge of tergite 



those Of Other Spe- of the seventh segment. 



cies where known. 

 This species is Japanese. 



D. frnhstorferi Martin, is in its venation clearly a member of 

 the tribe Davidius. But the reduced anal area of the hinder-wing, 

 and the characters of the male anal appendages suggest to me 

 that it may require transference to a distinct (and new) genus, as 

 already hinted by Ris. 



For the rest D. lunatns (Bartenef), D. aberrans Selys, and 

 D. zallorensis, have a yellow mark on the occiput ; the first of 

 these is Manchurian, the two others (probably conspecific) are 

 from the Himalayas. 



D. davidi Selys, from S. China and Assam, D. ater Selys, and 

 D. cuniculus Ris, both from Japan, have a black occiput. 



Lastly D. bicornutus, also from Japan, is larger than the other 

 species, is known only from a female specimen and is of doubtful 

 generic position. 



Length of abdomen of c? 31 mm., of hinder-wing 26-5 mm. ; 

 length of abdomen of 9 28 mm., of hinder-wing 28*5 mm. 



Group Cyclogomphus. 



It is impossible to give a really satisfactory definition of this 

 tribe, apart from sexual characters. None the less I am per- 

 suaded that it is a true phylogenetic entity. 



The tribe is characterized by the anal appendage of the 

 male. The upper pair are small, nearly parallel to one another, 

 and often brightly coloured. They are often provided with a 

 strong ventral projection. The lower appendage has its branches 



