136 EAST AFBICAX ODOXATA— CALVERT. vol. xviii. 



triangle free, two posttriaugular rows; inner side of triangle lying 

 sligbtly beyond the arculus (a distance equal to that part of the areu- 

 lus from its lower end to the origin of its sectors); sectors of the tri- 

 angle united at their origin. 



The female differs from the maie as follows: 



Lower half of median dorsal carina yellowish. Yellow of thorax 

 brighter. Abdomen shaped much as in the female of 0. hrachiale; 2 

 with a small dorsal yellow s])ot in front of the spot corresponding to 

 that described for the male; 7 with a small lateral spot; 10 with a small 

 dorsal spot. Sides of 8 dilated. Appendages a little longer than 10, 

 yellow, straight, apex acute. Vulvar lamina not prolonged beyond 

 apex of 8; margin entire, not bent in the manner described for 0. 

 hrachiale. Front wings with 13-11 autecubitals, 8-9 postcubitals. 

 Hind wings with 10-11 autecubitals, 11) postcubitals, one median cross 

 vein, inner side of triangle in prolongation of arculus; sectors of tri- 

 angle separated (right wing) or united (left wing) at their origins. 



Measurements of Orthefrum ivrigMii. 



I 



Total length 



Abdiimeu (incl.app.) 



Frout wing 



IlMid wing 



Pterostigraa 



Superior appendages , 

 Appendages 



Male. 



Female. 



Locality. — One male and one female in the National Museum collec- 

 tion, from the Seychelles, collected by Dr. W. L. Abbott. 



ONYCHOGOMPHUS COGNATUS, Rambur. 



Gomphus cognatus, Eambur, ^'ev^., p. 167, 1842. 



Onychoijomplim cognatus, Selys, Bull. Acad. Roy. Brux., XXI, Pt. ii, p. 38 (Syn. 



Gomph., p. 19), 1854; Monog. Gomph., p. 56, 1858. — Karsch, Ent. Nach., XVI, 



p. 377, 1890. 

 Lindenia cognata, Kirby, Cat. Otlon., j). 59, 1890. 



Two males in the National Museum collection, from Kilimanjai'O, 

 belong to this species, but differ from the description of the male given 

 by Baron de Selys ^ as follows: 



The dark marks of the face and lips are brown. In one male the 

 "large raie transverse en avant, au sommet du front" is wanting. 



There are no spines on the occiput. 



There is a group of 6-8 black denticles on each side of the upper 

 surface of the frons. 



The thoracic stripes are brown; the median dorsal bands are not 

 broad and do not join the antehumeral bauds; there is a stripe on the 

 second lateral suture, and a stripe from the spiracle to between the 



' Monog. Gomph., p. 57. 



J 



