ii,2 Mr. G. Meade- Waldo on 



Ducke (Zcitsclir. wiss. Ins. Biol. i. p. 175, 1905) treats of 

 the nocturnal habits of M. idalia. The same author, wlio 

 examined the types of Brazilian bees described by Smith 

 (Deut. ent. Zeit. p. 363, 1910), leaves only R. idalia in the 

 genus, relegating M. bituherculata, which was selected by 

 Cockerell as the type (Proc. Phil. Acad. p. 374, 1900), to 

 Jfidictus. Of the species described as Megalo}>ta by Smith 

 at later dates only il/. 2>M?7)M?'a<a (1879) can remain in the 

 genus, and its inclusion is open to question ; the remaining 

 ^^pecies work out mainly as jtroposed by Diicke (/. c), e. g., 

 J/, nigrofemorata and M. ianthina go into Ilalictus sens, lat., 

 while M. 2^dosa and M. cuprifrons belong to the cacosoma 

 group of species in that genus. M. ornata, a brilliant 

 metallic-green insect, has nothing whatever to do with the 

 genu?, and probably needs a new one. M. vivox has quite 

 lightly been placed as a variety of Aiigochlora atropos. 

 Smith, though I do not agree with Ducke in synonymizing 

 Augochlura with Halictus. 



Key to the Species. 



?$• 



1. (2) Black species, non-metallic. Length 



13 mm cherazoii, Vacli. (1904). 



2. (1) Testaceous species, head and thorax 



with some metallic iridescence. 



3. (4) Cheeks armed with a conspicuous 



tubercle ; clypeus much broader 



than long. Length 15 mm genalis, sp. n. 



4. (3) Cheeks unarmed. 



5. (8) Enclosed area well developed ; hind 



spur with six well-developed spines. 



6. (7) Joint 3 of antennse longer than 4, as 



long as 6. Length 17 mm fornix, Vacli. (1904). 



7. (6) Joint 3 of antennae short, not longer 



than 4. Length 14 mm sodalis, Vach. (1904). 



8. (5) Enclosed area very narrow, hardly 



more than linear ; hind spur with 

 four spines. 



9. (10) Postscutellum almost as long as 



scutellum, clypeus only sparsely 



punctured chaperi, Vach. (1904). 



10. (9) Postscutellum only half as long as scu- 

 tellum, clypeus coarsely punctured . idalia, Smith (1853). 



M. cuprea, Friese (1911), is possibly a variety of M. idalia. 



1. (4) Black species. 



2. (3) Thorax and abdomen with faint 



coppery and purple iridescence. [=r?>^j/?', Fr. (1911). 

 Length 14 mm purj>uratu,iivaii\x{\67\i) 



