W. M. DAVIDSON 37 



is .slightly concave below the antennae, the facial knob protrudes beyond the 

 antennaltubercle, below the knob the face recedes. Eyes bare. Occiput sil- 

 very pollinose, white i)ilo.se. 



Thorax and scutellum shining bluish-black, pik; white. Wings exf-cHnhag the 

 abdomen, hyaline, stigma light amber. Halteres pale }a>llow. Tegulae whit(!. 

 Legs testaceous, femora except apices black; hind libiac with an obscure dark 

 brown ring at apical third; pile of legs whitish. 



First abdominal segment shining metallic g7"cen. Second segment shiin'iig 

 metallic green, posterior border and a median emarginated i)roj(>ction opatiue 

 black. 'I'liird segment similar to preceding, excejit that the shining emargi- 

 natioii is narrower and reaches deeply into the opaciue jjortion. Fourtli 

 segment shining metallic green, with two oblique opaque black sjiots which 

 touch the margin at the posterior angles of the segment, and do not (juitc; 

 reach llie middle of the segment at tlunr anterior ends. Fifthsegmentshining 

 metallic green. The opaque bands of the second and third segments narrowly 

 reach the lateral margins and in the middle reach be3'ond the middle of the 

 segment. Pile of abdomen white. 



Length, 6.5 to S mm. 



Descril)C(l from ten specimons collected in the vicinity of 

 Alhiunbra, California, and from one s])eci(nen reared from the 

 ess iit Alhambra, 1920. 



Holotype (male) and allotype (femakO in the U. S. National 

 Musemn. 



The female^ may be recognized from that of other species treat- 

 ed in this paper l)y the greenish abdominal l)an(ls and pimctate 

 facial pollen; from M. stegnum 1)}^ the longer facial stripe. 



In general this species approaches M. f^fcgninti more nearly 

 than any of the others. Both have punctate pollen on the face 

 and the black hairs of the fore til)iac are thickened. In stegnum 

 the shining alxlominal spots are greeenish or greenish-gray in 

 l)oth sexes, in chactopoda those of i\w male are distinctly bronze. 

 That the two sexes above described under this name belong to- 

 gether has been proved bj- l)reeding exi)eriments. 



Melanostoma Ontario new species (Text-fig. C) 



IVLale. Antennae brownish black; third joint oval, twice as long as wide, 

 yellowish at the base below; arista bare, black. Vertex black, black jjilose. 

 Frontal triangle black, obscurely shining; pile black, of moderate length. Face 

 whitish jiollinose, in obscure ripple-like formation; in the middle a bare shin- 

 jug bluish stripe not reaching base of antennae. Profile below antennae 

 shal'owly excavated, the facial tubercle protruding slightly beyond the anten- 

 nal; below this concave, the epistoma protruding eciually witli the facial 

 tubercle; thus the face is perpendicular in profile. Cheeks shining bhush with 

 scant white jwllen, white pilose. Eyes red, bare. Occiput silver}' pcjlinose; 

 pile bi>low white, above fuscous. 



TRANS. AM. ENT. SOC, XLVTII. 



