160 



tarsi whitish yellow, rest of front tibiae and the tarsi brownish (other 

 pale markings as in $ ). 



Eighth sternite similar to that of H. Cressonii but the stem shorter 

 and the lobes more developed (as long from the base of their expansion 

 as their stem). Membraneous flap of seventh sternite more developed and 

 hairy, the teeth of the other flap fewer and larger, more or less hooked 

 at the end. 



Length about 5.5 mm. ; wing 4 mm. 



Described from 16 $ and 1 S taken in the vicinity of Lake 

 Merced in the sand dime district of San Francisco, CaL, 1 9 

 July 17, 1903 (F. E. Blaisdell), remainder August to Sept., 

 1910, (J. C. Bridwell). 



A very distinct species related to H. conspicuus (Metz), 

 Cressonii {Cocker ell) and ru dh c ck i ae {Cockerell) . The female is 

 distingriishable by the large head and the translucent margins 

 of the abdominal segments while the male may be separated 

 from that of conspicuus by the absence of the peculiar flattened 

 impression oyer the basal portion of the clypens, lower part of 

 supraelypeal area and adjacent sides of the face; the snpracly- 

 peal area is narrower and the scape is less expanded and has 

 far less yellow on it, the white hair bands on tergites 1 and 2 

 present in maritimns and not in conspicuus. H. ruclhechiae 

 (Cockerell) S is also similar but has the baso-lateral areas of 

 the propodenm well defined by a carina separating them 

 from the posterior face. Both these species which resemble 

 maritimus most closely haye the eighth sternite quite different, 

 as may be seen from lEetz' figures. Apparently Hylaeus Ste- 

 phensi (Crawford) is yery close to this in the structure of the 

 hidden sternites but the face markings are quite different in 

 both sexes. 



Hylaeus oregonensis n. sp. 



I have a form of this genus wliicli is represented in my collection by 

 two $ and two $ collected in the high Cascade Mountains of Oregon, 

 Mount Jefferson (Bridwell), which seem to differ but little externally 

 from what I have identified as H. polifolii except that the reticula- 

 tions of the propodeal basal area and particularly the basolateral areas 

 are more strongly developed and the clypeus at the summit seems a little 

 broader. I had supposed that this would prove to be nevadensis, but 



