358 Mr. F. Smith on the Genus Centris. 



culate, the flagellum filiform, the first joint gradually narrowed 

 to its base ; the labial palpi four-jointed, the two basal joints 

 elongate and flattened, the first longer than the second, the 

 third and fourth minute and attached to the second joint near 

 its apex ; the maxillary palpi four-jointed, the first and fourth 

 joints shorter than the intermediate ones ; the mandibles stout, 

 and with four blunt teeth in the females. Thorax : the anterior 

 and intermediate tibise with a single spine at their apex; the 

 posterior pair with two spines, the inner one pectinated : the 

 anterior wings with one marginal and three submarginal cells ; 

 the marginal cell oblong, nearly as long as the three sub- 

 marginals united, widest in the middle, tnmcate at the base, 

 and more or less rounded at the apex, from which an appendi- 

 cular nervure is emitted, which sometimes runs nearly to the 

 anterior margin of the wing ; the first submarginal cell is 

 divided by a more or less distinct transverse, perpendicular, 

 false nervure; the second cell is wider than the first, and 

 narrowed towards the discoidal cells, receiving the first re- 

 current nervure towards the first submarginal ; the third sub- 

 marginal much narrowed towards the marginal cell. 



Note. The mandibles tridentate in the males of many species. 



1. Centris furcata. 



Centris furcata, St.-Farg. Hym. ii. p. 151, J . 

 Bombus furcatus, Fab. Syst. Piez. p. 350. 



Hah. Brazil ; Demerara. 



The male only differs in having the scape of the antennje 

 in front, the clypeus, the face on each side of it, and the labrum 

 yellowish white. 



2. Centris denudans. 



Centris denudans, St.-Farg. Hym. ii. p. 150, pi. xx. fig. 1, J . 

 Trachina denudans, Latr., Schomb. Faun, et Flor. Brit. Guiana, p. 591. 



Hah. Brazil (Tapajos, Ega) ; Ecuador. 



The male differs from the female in having the clypeus and 

 labrum yellow, and in having the anterior tibise and tarsi 

 clothed with ferruginous pubescence. 



3. Centris thoracica. 

 Centris thoracica, St.-Farg. Hym. ii. p. 168, 5 . 

 Hah, Brazil; Rio Grande. 



4. Centris pulverata. 

 Centris pulverata, St.-Farg. Hym. ii. p. 161, 5 • 

 Hah. St. Paulo (Brazil). 

 I have seen the type specimen of this species. It is 1 inch 



