592 PROCEEDINGS OF THE ACADEMY OF [Aug , 



The female N. americana is easily distinguished from the red species 

 of Gnathias and Nomada s. str. by the strongly punctured abdomen: 

 Kirby says nothing about this, and it is with some hesitation that I 

 follow Robertson's identification of the species. 



N. articulata, Smith (cJ^ from Brookings, S. Dak., June S, 1891) has 

 a long spine on the anterior coxa, and belongs to Centrias. The hind 

 femora are arcuate, and the ground-color of the abdomen is mainly 

 red. This specimen of A^. articulata was identified by Mr. Fox, who 

 gave it to me; but I find that it is not typical, and in fact Smith's 

 description of articulata applies to the ordinary male of americana . 

 Kirby, as understood by Robertson. Hence, if any one should wish 

 to discard Kirby's name as of uncertain application, articulata w411 be 

 the proper name of the insect. I do not believe that valida, Smith, 

 which has priority of place, is applicable. 



The South Dakota insect, just referred to, may l^e described thus: 

 Nomada americana dacotana subsp. n. 



d". — I^ength about 9^ mm.; mesothorax largely dark red, leaving a 

 broad median black band; lower inner angle of second submarginal 

 cell produced; abdomen light red with yellow bands; basal half of 

 first segment, and apical portion more or less, black; first segment with 

 a yellow band narrowly interrupted in middle ; band on second segment 

 greatly narrowed but continuous in middle. 



Hab. — Brookings, S. D., June 8. Also two specimens with band on 

 second segment interrupted, marked "Colo., 2,076," in National Mu- 

 seum. Also three males from ^lontana (Coll. of Acad. Nat. Sci. 

 Phila.). 

 Nomada rubicunda (Oliv.). 



This is also a Centrias. I have before me six females collected by 

 Mr. Viereck in New Jersey; one at Clement on, ]\Iay 16, 1897, five at 

 Riverton, April 29. The insect is easily distinguished from americana 

 by the light bands on the apical half of the abdomen, these bands in 

 the New Jersey form l)eing creamj^-whitc. The basal nervure is a 

 little basad of the trans verso-medial. 

 Nomada (Heminomada) obliterata, Cress. 



A female from Indiana (Nat. Mus.) bears the Bakerian number 2,003. 

 The species goes west even to Montana, as shown by two males in 

 Coll. of Acad. Nat. Sci. Phila.. One of them, very curiously, has 

 a triangular areolet on both sides at the beginning of the first 

 recurrent nervure. 



The following species are small (all under 10 mm. long), with numer- 

 ous clear-cut yellow or white bands on abdomen : 



