348 THE CANADIAN ENTOMOLOGIST 



groups of 2 or 3 or in undulating lines at the sides of the segments. 

 On the 3rd and 4th segments these punctures are crowded together 

 so as to form an undulating band, leaving a smooth shining spot 

 on each side at the base, and a wide, triangular, sparingly punctured 

 area in the middle. Punctures in the apical segment crowded to- 

 gether so as to form triangular patches on each side, leaving the 

 middle space sparingly punctured." Length: 35 mm. Width: 13 

 mm. Habitat: West Africa; N. Nigeria. 



Var. waterhousei subsp. nov. "Thorax brassy. Elytra very 

 dark brown, with blue reflections." Habitat: Damaraland. Mr. 

 C. O. Waterhouse in Ann. Mag. Nat. Hist. No. 82, p. 248 gave 

 this variety without a name, and I have taken the liberty of affixing 

 one to it, the characters given seeming sufficient to warrant it. 



A GROUP OF AMERICAN HALICTINE BEES SIMULAT- 

 ING THE OLD-WORLD GENUS NOMIOIDES. 



BY T. D. A. COCKERELL, BOULDER, COLORADO. 



The gaily-marked little Halictine bees of the genus Nomioides 

 are widely distributed over the Old World, even extending to 

 Australia (iV. perditellus Ckll.). They are extraordinarily like 

 our American species of Perdita, but structurally are so distinct 

 that we can hardly suppose that there is any particular affinity. 

 More recently, however, there has been found in South America a 

 group of Nomioides-Vike insects which might almost be referred 

 to the Old World genus, did they not possess a sharply pointed 

 marginal cell as in Halictus. This affords another instance of 

 similarity between neotropical and Old World insects, which may 

 be due to common descent or to '/convergent evolution," or to 

 both. The group referred to, with ten described species, has been 

 found in the Andean region, but it now appears that it extends 

 northward to Panama. The following new species has been col- 

 lected by Mr. Busck. 



Halictus xanthinus, n. sp. 



9 . — Length 5 mm. or a littlie over; head and thorax brilliant 

 emerald green; mandibles pale yellow; clypeus ferruginous in 

 middle and dusky reddish apically, but above and at sides green; 



October. 1918 



