394 Annals of the South African Museum. 



hind winfj;. Pruinosity of male appearing early on abdomen, very late 

 on thorax. S , ^bd. 31, hdw. 33, jit. 3 mm. ? , 27, 31, 3 . 0. caffrum. 

 Thoracic sides with but one distinct whitish stripe, behind humeral 

 suture, lined with black in ventral half and gradually obscured dorsally. 

 Thorax otherwise similar to preceding species, only tliere is no trace of 

 a dorsal black stripe and the general colour has more of greenish and 

 less of ferruginous shade. Lateral abdominal black bands broad and 

 complete in male ; narrow and not touching latei-al carina in middle of 

 segments, but often not interrvipted in female. Face and frons as in 

 preceding species. Pterostigma longer, broader and generally lighter 

 in colour as in preceding species. Base of wings similar. Pruinosity of 

 male as in preceding species. ^ , Abd.29, hdio.30, pt. > 3 mm. 5,27, 

 29, > 3 .......... 0. chnjsosti^ina . 



8. Slightly larger species. Male witli internal and external branch of humule 

 of about equal length. Thoracic pattern in mature but not yet extremely 

 pruinose males an ante-humeral and two lateral greenisli stripes on black 

 ground ; in female black colour much reduced, to vestige of a line at 

 median suture, incomplete ante-humeral and humeral and parts of 4 to 5 

 lateral lines. In immature males, and especially females, the sides are 

 wholly greenish yellow with at most vestiges of black lines. Frons dull 

 olivaceous to bluish grey in mature males, greenish yellow in females, 

 with black basal Une, broader in males. (J , Abd. 28, hdw. 29, pt. 3 mm. 

 to33, 33, 3-5. ?, 25, 28, 3 to 31, 32, 3-5 .... 0. guineense. 



Smaller species and smallest Orthetrum of the present fauna. Internal 

 branch of hamule in male decidedly longer than external branch. 

 Thoracic pattern in mature, even fully pruinose males somewhat variable 

 and with irregular light green spots ; at dorsal end of mesepimeron, 

 dorsally and ventrally from metastigma on metepisternum, posterior 

 and dorsal half of metepimeron. Female very similar to preceding 

 species, not always readily distinguishable, the differences Ijeing only 

 relative ; smaller size and still more reduced dark colour on thorax, the 

 lines being mostly indicated by faint vestiges only. Face and frons 

 ■whitish in male, .light yellowish in female ; basal black line of frons 

 bi'oad ; not rarely fine black lines on anterior ridge of frons end around 

 anterior flattened spaces. ^ ? , Abd. 29, hdw. 30, pt. 3 mm. 0. Abbotti. 



Orthetrum trinacria, Sclys, 1841. 



S. Afr. Mus. : 1 9 , Johaunesburg, TraDsvaal (C. H. Pead) ; 1 ?, 

 Lorenco Marques (12 . xii . 1911). 



This largest species of Orthetrum kuown from the present fauua is 

 easily identified by its abdominal pattern, and when pruinose, by the 

 large whitish pterostigma, hyaline base of wings, very elongate 

 abdomen with basal segments much inflated. The species was first 

 discovered in Sicily, but it seems that it has not been obtained again 

 from this European island for the last seventy years. It is probably 

 most frei|uent in desert regions such as Mediterranean Africa and 



