DIPTERA OF BAJA CALIFORNIA. 605 



of Rhaphiomidas. The bristles of posterior angles of 

 thorax are, as a rule, yellowish, but sometimes somewhat 

 blackish; those of hind border of scutellum, however, are 

 blackish in all of my specimens. The ground color of 

 whole body is blackish, thorax and scutellum gray poUi- 

 nose, leaving a pair of closely approximated dark vitt« 

 abbreviated behind. Abdominal segments two, three, 

 and four are bordered on about posterior one -third with 

 yellowish, the yellow widening laterally on second. First 

 segment very narrowly yellowish on hind border, espe- 

 cially laterally. Legs colored as in acton (pale or yellow- 

 ish, the femora except tips darker), macrochcet^ of mid- 

 dle and hind legs blackish or brown, those of front legs 

 yellow. (In acton, the macrochsetge of the legs are en- 

 tirely yellow.) The last three segments of abdomen are 

 more or less yellow in ground color, but appear blackish 

 from being clothed with the short, appressed, anteriorly 

 directed, black hairs. Pile of rest of abdomen whitish or 

 yellowish. Wings clear. Antennee yellowish, third joint 

 more or less reddish, sometimes the basal joints brown- 

 ish. Pile of thorax, occiput, face, front, coxae, and ster- 

 num yellowish, that of latter more whitish. The middle 

 and front tibiae and tarsi are clearer and lighter yellowish 

 than those of hind legs. Length, 21 to 26 mm. 



Although my six specimens are all females, and my 

 eleven specimens of xanthos are all males, and moreover 

 both were largely collected at the same time and place, 

 still I do not believe that I am describing two sexes of the 

 same species. The sexes of Rhaphiomidas appear to 

 closely agree in coloration. Coquillett assures us that 

 the sexes of acton are alike in coloring. Besides, xanthos 

 comes much nearer to acton in coloring than it does to 

 mellifex, and we know that it can not be the male of 

 acton. From mellifex it further differs in the macro- 

 ch^t^ of scutellum (and middle femora) being yellow. 



