MASTOE. — MNASILTJS. 569 



Hab. North America, Arizona 1 2 . — Mexico, Milpas in Durango (Forrer), Las Vigas 

 (coll. Schaus). 



Mr. Forrer sent us a worn pair only of this distinct species from Milpas in Durango ; 

 Mr. Schaus's collection, however, contains three males from Las Vigas in good 

 condition. It may at once be distinguished from all the allied forms by its conspicuous 

 orange hairs on the head and palpi, and the ochreous fringe to both wings. 



For the genitalia of the male, see Tab. C. tig. 36. 



b. Primaries of the male without a brand. 



3. Mastor perigenes, sp. n. (Tab. c. figg. 37, 38, 6 .) 



Alis nitente fuscis, unicoloribus : subtus anticis obscure fuscis, costa et apice sordide ochraceis ; posticis coloris 

 ejusdem, venis omnibus pallidioribus, strigis duabus longitudinalibus a basi, una ad marginem externum 

 juxta apicem, altera minus distincta angulo anali propiore (interdum absente), albidis, plica ad marginem 

 internum fusca ; corpore et palpis subtus canescentibus ; ciliis griseis. 



Hab. Mexico, Rincon in Guerrero (H. H. Smith). 



Two males are all we know of this insect, which may be easily identified from its 

 allies by the longitudinal whitish streaks on the secondaries beneath. In one example 

 the inner streak is absent. It has no brand on the primaries. M. perigenes closely 

 resembles Thymelicus bicolor, Mabille, which we take as the type of another genus, but 

 has a shorter apical joint to the palpi and the underside of the secondaries is differently 

 coloured. For the genitalia of the male, see Tab. C. fig. 38. 



MNASILUS, gen. nov. 



The single species referred to this genus is widely distributed in Tropical America. 

 This insect is closely related to Megistias, but differs from it in having a conspicuous 

 pencil of hairs on the primaries in the male, the genitalia also being peculiarly formed. 



The antennas are half the length of the costa, and have a rather stout club, termi- 

 nating in a long crook. The third joint of the palpi is very short, stout, and bluntly 

 conical. The primaries are slightly produced at the tip, the apex blunt, the costa very 

 feebly arched towards the base ; the cell is much less than two-thirds the length of the 

 costa; the discocellulars are oblique, the upper one slightly longer than the lower, 

 the latter being of the same length as the third median segment ; the lower radial is 

 slightly depressed at the base ; the first branch arises from the middle of the median 

 nervure, the second a little before the lower angle of the cell. The secondaries are 

 feebly produced at the anal angle ; the discocellulars are oblique and very faint. The 

 body is rather slender. The middle tibiae are spined; the hind tibise have two pairs 

 of spurs. The primaries of the male (Tab. C. fig. 41) have a conspicuous pencil of long 

 hairs just below the submedian nervure before the middle, but there is no brand. 



