340 H. Friese. 



with either of which it may be identical, but from the descriptions of these two species 

 the present one ditiers in several respects, which may, however, be due to lack of greater 

 detail. 



2. Centris pallida Fox. 



i8gg. Centris pallida Fox, 9, Natural sc. Philadelphia, pag. 66. 



9. Black, densely clothed with grayish white pubescence, that on vertex and 

 thorax above slightly pertaining to fulvous; median and bind legs with black pubescence 

 on tibiae and first tarsal Joint; remaining tarsal joints reddish; clypeus with a triangulär 

 yellow mark; labrum covered with dense pile, that on base whitish, at apex brownish; 

 mandibles black, with pale pile at base externally; first Joint of flagellum slender, almost 

 as long as the five following joints; tegulae testaceous; fore tarsi fringed with pale 

 fuscous hairs, the pubescence of the inner side of first Joint brownish; abdomen with 

 the pubescence of dorsal surface short, hoar-frost-like, except on apical half of fifth 

 Segment where it is black; ventral segments 2 — 4 fringed at apex with long white hairs, 

 the fringe of segment 5 being dark brown; the ventral segments medially are supplied 

 with darker dense pubescence, which, when viewed from the side, extends from base 

 of second segment to apex of fourth; sixth segment with brownish pubescence, the 

 pygidiuni elongate, narrow, reddish at base, with a broad flat fold or swelling running 

 from apex to near base; wings subhyaline. Length 16 — 17 mm. 



Arizona: Phoenix. Five specimens given to me by Dr. H. G. Griffith, by whom 

 they where collected in May, i8g8, pn the flowers of the »Palo Verde«, Parkinsonia 

 Torreyana. Dr. Griffith states the bees were abundant and easily captured, allowing 

 the collecting bottle to be slipped up quite close to them and the stopper then used in 

 such a manner as to knock them into the bottle. This apparent lethargic condition of 

 the specimens is quite unusual for species of Centris, as from all accounts they are 

 usually very rapid flyers and easily disturbed, after the manner of Odonata. I can 

 testify from experience as to the alertness of two of the West Indian species C. hae- 

 mnrrhoidalis and C.fasciata. The abdomen is densely pruinose above. 



3. Centris morsei Ckll. 



1897. Centris Morsei Cockerell, d", Proc. Acad. Natural sc. Philadelphia, pag. 355. 



New Mexico: Mesilla. Quite distinct by its large size (21 mm.) and the pale red- 

 dish-yellow bands on dorsal segments i and 2. 



4. Centris marginata Fox. 



i8gg. Centris marginata Fox, <S, Natural sc. Philadelphia, pag. 67. 



cT. Black; ventral segments laterally lestaceous-yellow, all the dorsals at apex 

 broadly margined with testaceous; flagellum slightly brownish beneath; clypeus, labrum 

 and spot between antennae at base of clypeus, bright lemon-yellow; mandibles reddish- 

 brown, with black tips; entire insect covered wMth pale gray pubescence, except the ab- 

 domen above, which is quite bare, excepting the extreme base of first segment; the 

 pubescence inclining to fulvous on top of head and thorax, and sufficiently thin on 

 dorsulum and mesopleurae to display the sculpture; front broad; first Joint of flagellum 

 about as long as the three following united; legs robust; pubescence of anterior tibiae 



