182 AMERICAN HYMENOPTERA. 



ship very largely on coloration and similarity of general ap- 

 pearance. A knowledge of the great color variation shown 

 by many species of this group should be enough to condemn 

 coloration as a basis for determining relationships with cer- 

 tainty. It is probable that those who have depended on 

 coloration in such classifications have, in most cases at least, 

 been compelled to depend on that or nothing because of lack 

 of material, especially of males, for dissection. It is particu- 

 larly desirable to know the characters of the male genitalia 

 in judging relationships, but other structural characters should 

 be considered in connection with them. In this paper, the 

 work of Radoszkowski has been followed as far as possible, 

 in the naming of the natural groups and also, for the most 

 part, in the naming of the accessory male genital organs. 

 Unfortunately, Robertson's division of the genus into Bom- 

 bus and Bombias is not likely to stand the test of critical 

 study for reasons given in another place. 



THE FAMILY BOMBID^. 

 Bombinatrices Kirby, Mon. Ap. Angl., I, 1802, p. 200 and II, p. 317. 

 Bombides Lepeletier, Hist. Nat. Insect, I, 1836, p. 436 and Psithyri- 



des Lepeletier, ibid, II, 1841, p. 423, 

 Bombidce Greene, Ann. Lye. Nat. Hist. N. Y., 1862, p. 168. 

 Botnbina Thomson, Opusc. Ent., I, 1869, pp. 7 and 11. 

 Bombidce Schmiedeknecht, Apidse Europaeae 1882-1884 (pp. 11^ and 



13^ and 263) and Psithyridce Schmiedeknecht, ibid (p. 12^ 



and 14^ and 390) . 

 Bombince Friese, Die Bienen Europa's (Apidae Europaeae) nach ihren 



Gattungen, 1895-1897 and PsithyrincB Friese, ibid. 

 Dalla Torre, Cat. Hym., X, 1896, p. 503, and PsUhyrince 



Dalla Torre, ibid, p. 565. 

 Bombides Ashmead, Proc. U. S. N. M., XXIII, 1901, p. 191 and Psi- 



thyridcs Ashmead, ibid, p. 192. 

 Ashmead, Trans. Amer. Ent. Soc, XXVI, 1899, pp. 54 and 



57, and Psithyrid(s Ashmead, ibid, pp. 54 and 58. 

 Bombince Robertson, Trans. Amer. Ent. Soc, XXIX, 1903, p. 176. 

 Bombidce Viereck, Trans. Amer. Ent. Soc, XXIX, 1902, p. 44 and 



Psithyridce Viereck, ibid, p. 45. 

 Bombince Schmiedeknecht, Hym. Mitteleurop., 1907, p. 22, and Psi- 



thyridce Schmiedeknecht, ibid., p. 23. 

 Bombidce Viereck, Trans. Amer. Ent. Soc, XXXII, 1906, pp. 224, 238, 



240, 242, 245. 



