ORTALID^E — SYSTEMATIC DISTRIBUTION. 45 



the only difference shown by the latter species is a somewhat 

 smaller length of the third antennal joint. Next to these are 

 some South African Rivellise, for instance, Rivellia atra Lw., 

 which have the third antennal joint a little shorter still ; all these 

 species, however, cannot be separated from Rivellia, as the dimi- 

 nution of the third antennal joint is a very gradual one, not 

 affording any distinct limit for a separation. 



Macquart's E pidesm a fascipennis, from the Cape, is likewise 

 but very little different from the typical Rivellise. The occiput 

 is somewhat more convex ; the third antennal joint has a some- 

 what sharper anterior angle, the thorax is comparatively a 

 little smaller, and the first section of the fourth longitudinal vein 

 shows but very little of the sinuosity, so characteristic of the 

 true Rivellise, and which renders the anterior part of the discal 

 cell more narrow ; at the end of the convex scutellum there are 

 two strong bristles ; whether the second pair of bristles, which 

 exists in the other Rivellise, is wanting here, or whether they 

 were accidentally broken off in the specimen I had before me, I 

 am unable to decide ; I rather incline to favor the former suppo- 

 sition. If I am right, Epidesma would deserve to be retained 

 as a separate genus ; in the opposite case, it would be better to 

 place Epidesma fascipennis in the genus Rivellia, because then 

 the whole difference between them would merely consist in com- 

 parative characters. 



Among the -species from the southeast of Asia, there are 

 several which are closely allied to Rivellia, but differ from the 

 typical species in the greater length and lesser breadth of the 

 marginal cell, a more straight third longitudinal vein, and a 

 hardly perceptible sinuosity of the first section of the fourth vein ; 

 moreover, the thorax is less strongly developed, so that their 

 stature shows some, although only a distant, resemblance to the 

 species of Stenopterina. They are easily distinguished by the 

 picture of their wings, which is very different from that of the 

 Rivellise ; it consists in a conspicuous black border along the 

 costal margin and the apex, not unlike that of Diacrita and 

 Molanoloma, while the Rivellise, besides the apex, which is mar- 

 gined with black, also have black crossbands. I propose for this 

 genus the name of Scotinosoma. 



Species having the first section of the fourth longitudinal vein 

 straight, must, most decidedly, be eliminated from Rivellia. 



