48 Myron Harmon Swenk 
latter has a broader and more closely punctured abdomen, dif- 
ferently sculptured metathorax (pits broader and better formed), 
unclouded wings, and more densely punctured scutellum, but he 
considers the two as allied. I regret that I am unable to figure. 
the genitalia of this interesting species. 
Colletes nudus Robertson. 
1898. Colletcs nudus Robertson, Transactions of the Academy of Science 
of St. Lowis, viii, pp. 43-44, 2 ¢ (March, 1898); original de- 
scription. i 
1904. Colletes nudus Robertson, Canadian Entomologist, xxxvi, no. 9, 
p. 275, 2, p. 277, ¢ (September, 1904) ; in table of Illinois species. 
1905. Colletes Vierecki Swenk, Ibid., xxxvii, no. 8, pp. 301-02, 2 (Au- 
gust, 1905) ; original description. 
?. Length 10-12 mm. Shining black, body almost bare. Eyes moder- 
ately converging below. Clypeus slightly convex, not sulcate, closely stri- 
ate-punctate. Supraclypeal area convex, shining, marginally with crowded 
punctures. Face crowded with good-sized punctures and with very short, 
erect, pale pubescence. Antennae black, the flagellum dull brownish dusky 
beneath, the scape deeply punctured, joint 3 a shade shorter than 4, de- 
cidedly shorter than 5, the proportion being 3.5:4:5. Median flagellar 
“joints as wide as long. Malar space linear, about one-ninth as long as 
wide. Cheeks rather coarsely and closely punctured except around the 
orbits, their pubescence very sparse and whitish. Vertex shining and pol- 
ished, finely and sparsely double punctured, its pubescence fairly long, pale 
and black intermixed, the former predominating posteriorly, the latter be- 
tween ocelli. Facial foveae large, distinct, encroaching on vertex. Pro- 
thoracic spine distinct, sharp, broadly subtriangular. Pubescence of a 
broad anterior thoracic border mostly grayish white and very short and 
thin, dense on a grayish mat on tubercles, that on entire disk mostly black, 
of very scattered, short, bristle-like hairs not nearly concealing the sur- 
face. A black scutellar fringe is followed by a pale one, and longer pale 
grayish hairs are on the postscutellum and down the sides of metathorax. 
Mesothorax anteriorly with a median impressed line and coarse, very 
close punctures becoming more separated posteriorly, decidedly more so 
on a very small disk. Scutellum shining, very coarsely and quite closely 
studded with round punctures, postscutellum with fine cancellate punctures 
and anteriorly a more or less evident row of irregular pits. Mesopleura 
with very large, coarse, striate punctures. Superior face of metathorax 
well defined by a rimmed angulation and with the usual shining pits, square 
medially. Enclosure polished, approaching a T-shape because of the very 
wide bowl and narrow neck, the former of these convex with lateral ridges 
and the latter with indistinct transverse rugae, the surrounding areas 
90 
