186 Annals of the Carnegie Museum. 



93. Oxyagrion basale Selys. 



(Plate III, figs. 54, 55.) 

 Oxyagrion basale Selys, Bull. Acad. Belg. (2) xli, p. 303. 1876. 



cJ 1 . The considerable number of individuals, which I refer to this 

 species, differ in the following respects from de Selys' description based 

 on a single male from " Bresil ": 



Quadrilateral on the front wings with the superior (anterior) side a 

 little longer, in others a little shorter, than the internal (proximal) side 

 and about two-fifths to one-third as long as the inferior (posterior) 

 side ; on the hind wings the superior side is longer than the internal 

 and half as long as the inferior. Black mid-dorsal thoracic band mar- 

 gined on each side in some by a yellow line. Often a superior black dot 

 on each side of abdominal segment 8 at two-thirds' length, black on 

 dorsum of 9 and 10 reaching to the hind end of each segment, or of 9 

 only, longitudinally divided by red in the anterior half only of 9. 

 Apices of the inferior appendages acute, curved upward and inward. 

 More or less well-defined pale green postocular spots dotted with black 

 similar to the black dotting of the thoracic dorsum. 



The younger males differ from the older ones (to which latter de 

 Selys' description applies) as follows : labium and rear of the head 

 pale yellowish, upper surface of the head reddish brown, as also are the 

 areas dotted with black, on which the greenish postocular spots of older 

 stages are present ; prothorax brown, with black lines occupying the 

 various grooves and sutures; thoracic dorsum yellowish-brown; no mid- 

 dorsal black band, inferior humeral spot, or lateral band, but numer- 

 ous blackish dots on the mesepisterna, less numerous on mesepimera 

 and metepisterna, absent from the metepimera ; a short black mark on 

 the upper ends of the humeral and second lateral sutures ; red of the 

 abdomen less brilliant; dorsum of 1 and 2 reddish-brown, of 7—10 yel- 

 lowish-brown ; a superior darker brown spot on each side of 9 and of 

 10, a transverse dorsal blackish streak on 10 ; pterostigma paler brown ; 

 legs yellowish, with a superior femoral and an anterior tibial blackish 

 stripe, or line, more or less interrupted. 



Subsequently the upper surface of the head and of abdominal seg- 

 ments 1 and 2 darkens and the greenish postocular spots appear before 

 the black mid-dorsal thoracic stripe. 



9 (not hitherto described). Labium, under and rear surfaces of 

 head, and genae pale yellow ; vertex and frons olive, the latter paler 



