304: Descriptions and Records of Bees. 



the third s.m. being much shorter. The mouth-parts are 

 those of Diadasia, and P. tricolor, like our North American 

 species of Diadasia, visits flowers of Cactaceje. The vena- 

 tional character holds well enough when we compare North 

 Axnei'icnn Diadasia with typical PtilotJirix, hut the Brazilian 

 D. inurihirta, Ckll., is intermediate, having the third s.m. as 

 in Ptilot/iri.v. D. sumichrasti vulpihirta, Cklh, also has a short 

 submarginal. Ptiluthrix agrees Mith the North American 

 genus Emphor, to which it is closely related, in lackiug a 

 pulvillus on the feet. On this basis, as well as the short 

 submarginal cell, Diadasia sumichrasti, Cressou, becomes 

 Ptilothrix sumichrasti. D. murihirta, on the other hand, 

 has large pnlvilli, and remains in Diadasia. 



Tlius the separation of Diadasia from Ptihdhrix may be 

 maintained, though the genera are extremely closely allied. 



It remains to consider the status of Ancyloscelis, which 

 has l)een often used for these insects, and of Melitoma, 

 Avhich is preferred by Ducke. It is now considered that 

 Melitoma is the prior name for Entechnia, Patton, which I 

 regard as a very distinct geinis. Anci/Ioscelis, Latr., 1825, 

 included no named species, and Ancyloscelis, Spinola. 1851, 

 is a synonym of Tetrapedia. In 1836, however, Ilaliday 

 published Ancylosceles (not Ancyloscelis) for a species 

 ursiiuis, taken by Lieut. Graves at S. Paulo, Brazil. The 

 specimen is probably in the W . W. Saunders collection at 

 Oxford. It was a male, 4^ lines long, with the region of 

 the mouth, the tegulre, and tarsi yellowish ferruginous. The 

 description might serve for the recognition of the species, 

 but the generic characters are not mentioned. So far as I 

 know the insect has not been collected since, and at present 

 we can only say that it is probably not a Ptilothrix or 

 Diadasia. In P. tricolor (Fr.) there is long hair on the 

 apical half of second joint of maxillary palpus, aud all aloug 

 the side of the third, while the fourth has shorter hair at 

 side. The joints of the palpus measure in microns : (1) 320, 

 (.2) 480, (3) 512, (4) 352, (5) 224, (G) 176. The paraglossje 

 fall about 480 microns short of end of first joint of labial 

 palpi. The hind spur is curved at end. 



Diadasia australis knabiana, subsp, u. 



$ . — Labrum, mandibles, aud broad apical margin of 

 clypeus bright chestnut-red; legs red, the femora dusky ; 

 apical bauds on abdominal segments 2-4 very well defined. 



Tehuantepec, Oaxaca, June 30 {F. Knab). I".S. Nat. 

 ^Museum. 



