270 [August, 



25 (26) Hind metatarsus on the outer surface nearly ahva^'s darlc or infuscate, 



hair-baud of 10th antenual joint narrow 



.... fer/nu/iiiaius v. Hag. 



26 (25) Hind metatarsus in most specimens clear yellowish ; hair-band of 



10th joint of the antennae Avider, extending usually, where longest, 

 to n point between ^ and i the length of the joint 

 .... hynlinatus v. Hag. 



27 (24) ^[esonotal punctures at least to a large extent remote — in some 



examples very remote ; abdomen narrow and elongate, nmre 

 cylindrical varieciatiif v. Hag. 



28 (13) Hair-band of lOlh antennal joint very wide, coverini;- the whole face 



of the joint except a narrow apical portion. 



29 (30) Mesonotal punctures stronger and coarser, base of hind tibiae above 



notably pale, yellowish dimidiatus v. Hag. 



30 (29) Mesonotal jmnctures finer, and the base of the hind tibiae above as a 



rule dark affinis v. Hag. 



Owing to their \ovy great variability and tlie fact tliat highly 

 aberrant examples occur in tlie species that follow after niger, a brief 

 table of genital characters is here added for these species, so that these 

 doubtful examples ma}' be rightly placed. 



1 (G) Stipites of the genital armature not grooved. 



2 (3) Armature ver^' wide, transverse, the hicinia in some aspects bifid 



.... din'sus K. 



3 (2) Armature slender, yellowish or orange in colour, the lacinia not 



bifid. 



4 (5) Lacinia produced back along the inner edge of the stipes for a distance 



about as great as that to which it is produced beyond their apex 

 .... punoticeps Th. 



5 (4) Lacinia not thus produced back 



.... lonffulus V. Hag. 



6 (1) Stipites with a great longitudinal groove. 



7 (8) Lacinia well chitiuized, brown or yellowish brown, without a large, 



thin membranous portion, extending about to the tip 

 .... Iiyalinatus v. Hag. 



8 (7) Lacinia with a large inner membranous portion, to a considerable 



extent quite pallid, and extending to, or almost to, the tip. 



9 (10) Form slender and elongate, mesonotum more or less remotely punc- 



tured ; three first abdominal segments usually with black or dark 

 bands, rarely the 2nd and 3rd with only fuscous markings in the 



middle vanei/atiis v. Hag. 



10 (9) Fol'm not slender ; mesonotum densely punctured ; abdomen some- 

 times with three entirely red segments, and most often with at 

 least one red one, but sometimes all are black-banded 

 .... ferniyi/iaius v. Hag. 



S. dimidintus is easily separated from ajfinis by the much longer 

 lacinia, and neither can be confused with any other of our species. 



