10 DIPTEEA. 



Abdomen without yellow markings; face in the middle with 

 three or four parallel, transverse, delicate grooves .... 7. 



4. Large species ; abdomen oval, with f our yellow spots in the J 



male,andtwosmalleradditionalonesinthefemale . . . ^to, Wiedem. 



Species of smaller or ordinary size and elongate form ... 5. 



5. Antenna3 elongated and separated at their hase catabombum, sp. n. 



Antennse short, the first joint not so long as the second ; an- 



tennse more nearly contiguous at their base 6 - 



6. Facelightlyanduniformlypollinose • mellinum,[Unn) 



Face, on the sides and the lower part of the f ront, covered with 



denseyellowpollen \ pruinosum, Bigot. 



7. Antenna3 black ; abdomen mostly opaque black melanocerum, sp. n. 



Antennse more or less yellowish ; abdomen largely shining . 8. 



8. First joint of the antennse not longer than the second . . . rugosonasus, sp. n. 



First joint of the antennae as long as the other two joints 



together; wings with narrow brown clouds on the cross- 



vems crenulatum, sp. n. 



l. Melanostoma stegimm. 



Syrphus stegnus, Say, Journ. Acad. Phil. vi. p. 163 1 ; Complete Writings, ii. p. 358. 

 Melanostoma tigrina, Osten Sacken, Western Dipt., in Bull. U.S. Geol. & Geogr. Survey, m. 

 p. 323 2 . 



Melanostoma tigrinum, Willist. Synopsis N.-Am. Syrphidaj, p. 47, t. 3. f. 8 \ 



Hab. United States, Washington 3 , California 23 , Colorado 3 , Kansas, Arizona 3 .— 



Mexico \ Omilteme 8000 feet, Amula 6000 feet, Sierra de las Aguas Escondidas 7000 



feet, all in Guerrero (H. H Smith), Ciudad in Durango 8100 feet (Forrer), Orizaba 



(H. H. Smith and F. JD. Godman). 



Numerous examples. The males agree quite with specimens from the United 

 States. The female, hitherto unknown, has the front broad above, pollinose, except on 

 the upper part, and with black pile ; the thorax more shining metallic blue ; the 

 tibiee yellow; and on both the third and fourtb abdominal segments there is a 

 narrow shining stripe, bisecting the black, as in the fourth segment of the male. The 

 male has some long black hairs on the outer side of the front and middle tibiae, which 

 are inconspicuous in the female. It is evident, from the light colour of the tibiae, that 

 Say's specimens were females. 



2. Melanostoma fenestratum. 



Syrphusfenestratus, Macq. Dipt. Exot. ii. 2, p. 103, t. 17. f . 6 1 ; Blanchard, in Gay's Hist. fis. y 



polit. de Chile, vii. p. 413 2 ; Philippi, Verh. zool.-hot. Ges. Wieu, xv. p. 746 3 . 

 Melanostoma fenesirata, Schiner, Reise der Novara, Diptera, p. 351 \ 



Hab. Mexico, Omilteme 8000 feet (H H Smith), Ciudad in Durango 8100 feet 

 ( Forrer).— South America 4 , Chili 1 2 3 . 



