A. TULLGREN, HYMENOPTERA ACULEATA FROM THE CAMEROONS. 447 



males has normally developed horns on the mandibulee, by 

 another these are wholly reduced. In the colonr the spe- 

 cimens differ a little from each other. The vertex is by one 

 male nearly onecolonred red, by the other it is perfectly 

 black. Of the females only one has the vertex entirely black. 

 All specimens differ in the colonr of mesonotuin. By one 

 specimen the mesonotnm is black, by another red only with 

 two very small black spöts at the anterior margin. Between 

 these two extremities the other specimens are transition- 

 forms. All specimens belonging to the Royal Mus. at Stock- 

 holm have the mesonotnm onecolonred black. That seems to 

 be the normal colonr. Of the specimens from the Cameroons 

 four have the abdomen entirely black; only by a single spe- 

 cimen the first abdominal segment is nearly all över red. 



Length o* 25 mm.; 9 20 — 22,5 mm. 



Exp. c? 46—50 mm.; $ 42—43,5 mm. 



(The largest male in the Roy. mus. at Stockholm mea- 

 sures in length 36 mm.) 



Geographical Distribution. — West-Africa: Cap— Guinea. 

 S. trispinosa Tullgr. n. sp. (Pl. 24, fig. 9 a — e.) 



This large and beautiful species is very nearly related 

 to S. cornuta but differs in several important characters. 



The collection contains a male and a female from Kitta 

 i 10 - 11 /* 1891). 



o 71 , $ — The best part of the head is reddish brown; 

 the vertex black. The thorax and the legs of the same co- 

 lour as by the preceeding species. The abdomen is black, 

 clothed with a very short black pubescence. By the male 

 the first abdominal segment has a reddish spöt on each side, 

 by the female these spöts are very large and run together 

 aronnd the petiole. The wings are dark fuscous with a bril- 

 liant violet effulgence in certain lights. Any darker band at 

 the margins of the wings as by S. cornuta is not by these 

 specimens. 



Probably this species varies in as ligh degree as S. cornuta. 



The clypeus is by the previous species broader than 

 high, by S. trispinosa it is higher than broad especially by 

 the male. 



The most characteristic detail in the structure of this 

 species is the armature of the head by the male The face 



