NEW OR LITTLE KNOWN NORTH AMERICAN BEES. 



Charles Robertson.* 



Prosopis thaspii, n. sp. 



5. — Agrees in size with the female of P. affinis; head in 

 front appearing more circular than usual, the eyes and vertex 

 more convex; eyes short and broad, meeting bases of 

 mandibles ; cheeks short and with the vertex rather strongly 

 produced behind the eyes; head shining and rather sparsely 

 punctured, except in front of ocelli ; an impressed line 

 extending forward from anterior ocellus ; mesonotum and 

 scutellum finely and rather sparsely punctured ; metathorax 

 rather strongly sloping, hardly truncate, inclosure rugose on 

 basal middle; abdomen shining, impunctate; insect black, 

 flagellum beneath, mandibles at tips and tarsi dull ferru- 

 ginous ; a short triangular spot on each side of face, two 

 spots on collar, sometimes wanting, and basal third of hind 

 tibiae, yellow ; the other tibiae also show a faint indication of 

 yellow at extreme base; wings subhyaline, uervures, stigma 

 and tegulae dark. Length 6 mm. 



Carlinville, Illinois ; 2 5 specimens, taken June 9th and 

 14th on flowers of TJiaspium aureum var. trifolialum. 



COLLETES NUDUS, U. Sp. 



5. — Black, shining, pubescence thin, pale, except on ver- 

 tex and thorax above, where it is blackish ; face punctured 

 densely below, more sparsely and coarsely above, sides, of 

 vertex shining, somewhat doubly punctured; clypeus coarsely 

 striate punctate, apex emarginate; labruin with five more or 

 less evident pits; mandibles, except base, rufo-piceus, space 

 between base and the eye narrow ; antennae black or nearly 

 so; prothorax with evident sharp spines; mesonotum punc- 

 tured closely in front, more coarsely and sparsely on disc, like 

 the scutellum; post-scutellum with a transverse series of sub- 



* Presented in abstract to The Academy of Science of St. Louis, January 



17, 1898. 



(43) 



