130 EAST AFRICAN ODONATA— CALVERT. voL.xvni. 



also some dififerences in color from 0. chrysostigma, but these are of 

 comparatively little importance. 



It is quite possible that tlie two species of Orthctriim described as 

 new iu tbis paper are iu reality identical with some of the species 

 described by Burmeister or Eambur. As, however, I am unable to 

 point out such an identity from the existing descriptions, it seems bet- 

 ter to describe and figure the present material under new names than 

 to run the risk of erroneous identifications. It is hoped that the present 

 descriptions and figures will sufficiently characterize the species in 

 question, so that those ha\'ing access to types of previously described 

 species may perceive the identity, if it exist. The genus Orthetruiu is 

 a difficult one, and a revision of its species, based on abundant material, 

 is greatly to be desired. I would suggest that the most reliable specific 

 characters are to be found in the genitalia of the male and the vulvar 

 lamina of the female, on the lines adopted by M. Albarda. 



ORTHETRUM BRACHIALE, Beauvois. 



Hbelhtla hracliialis, Beauvois, Ins. Afr. Amer., p. 171, Neur., pi. 2, fig. 3, 1805. — 

 Eambur, Nevr., p. 62, 1842.— Selys, Auu. Soc. Ent. Belg., XXXI, p. 21,1887.— 

 GerstXckek, Mitt. Naturh. Mus. Hamburg, IX, 1, p. 5, 1891. 



Orthetrum brachiale, Kirby, Cat. Odon., p. 36, 1890. 



Male. — Vertex dark brown or black. Frons roughly punctate, vary- 

 ing from light olive green to dark brown, according to age; the carinae 

 margining the "shield" are yellow in younger individuals; of the same 

 color as the frons in older ones. Kasus and rhinarium light olive green 

 to obscure luteous, according to age. Labrum obscure lute<ms, its 

 margin sometimes black. Labium varying from luteous, unsj)otted, to 

 the mentum black; lobes with a black spot on the inner margin. Occi- 

 put dark brown or black. 



Prothorax pale green with small brown marks in younger males, 

 pruiuose in older; hind margin more or less emarginate in the middle. 



Thorax (in dry specimens at least) light green in young males; brown 

 and paler on the sides in those somewhat older; median dorsal carina 

 blackish at ajiex ; dorsum of thorax somewhat darker alongside of this 

 carina, and occasionally forming a complete stripe from the anterior 

 border to the antealar sinus ; a blackish antehumeral stripe not reacliing 

 the anterior mesothoracic border below nor the antealar sinus above; 

 a complete humeral stripe in the young males, giving off an anterior 

 branch halfway up, in older males the humeral stri^je exists only near 

 the feet; a short black stri.pe in front of the spiracle, and on the lower 

 part of tbe second lateral suture; latero-ventral metathoracic carina 

 shining black. In old males the thorax is almost entirely pruinose. 



Feet black, trochanters, bases of femora, front femora interiorly, 

 second tibiae superiorly, often pale. 



Abdomen, viewed from above, inflated at the base, compressed, nar- 

 rowing to the base of 4, thence widening to G, thence tapering to ajjexj 



