18 DIPTEKA. 



blackish-green, with an oval yellow spot on each lateral margin. A smaU spot on the outer end of the 

 suture and another on the postalar caUus yeUow. Pleuras blue-black, whitish-pollinose. Abdomen 

 narrow, elongate, with nearly parallel sides ; the first segment, the margins of the followmg ones, the 

 fifth segment, and the hypopygium shining black; for the rest opaque black, with three pairs of smaU 



a, the distal three joints of the tarai blaekish ; 



yellow spots. Legs : two anterior pairs yeUow and brown, 



hind pair black, the knees somewhat yellowish, the first three joints of their tarsi 

 subhyaline, the costal cell lightly clouded, the subcostal ceU brown. 

 Length 10-11 miUim. 



Hab. Mexico, Venta cle Zopilote in Guerrero 2800 feet (H. H. Smith).— Brazil, 

 Chapada \ 



Five specimens. 



I have compared these with the ones mentioned by me 1 from Brazil, as perhaps 

 belonging to S. gastrostactus, Wiedem., and find them identical. These male specimens 

 bear a remarkable resemblance to the females of Ocyptamus trigonus, known only from 

 that sex; and I suspect that they belong to the same species, notwithstanding the 

 marked differences (compare Schiner, Eeise der Novara, Diptera, p. 347). 



9. Syrphus decipiens, sp. n., s . 



Frontal triangle opaque yellowish-green, yeUow below ; pUe black. Antennas red : third joint orbicular, 

 brownish above. Face and cheeks yellow, the former with yeUowish pUe and white pollen on the sides. 

 Mesonotum glaucous-green, a Uttle shining, with yeUow pile. ScuteUum yeUow, with long black pile. 

 Abdomen narrow, elongate, with paraUel sides ; first segment shining blue-black, with the sides yeUow ; 

 second segment opaque black, the hind margin shining, and before the middle with two yeUow triangles 

 meeting at their points in the middlo to form a cross-band ; third segment with a pair of slender triangles 

 on the front margin, not meeting in the middle, more or less coalescent on the sides with an entire cross- 

 band, the black in front of the cross-band forming a slender crescent — the posterior margins of the yeUow 

 band oblique, angulated in the middle, the black behind it as that before, opaque, except on the hind 

 margin ; fourth segment similar, thc crescent smaUer, tho angle behind more acute, the shining portion 

 extending forward acutely in the middle ; fifth segment with a large yeUow spot on each side : hypo- 

 pygium shining black. Legs yeUow ; hind femora broadly blackish in the middle ; hind tibiae black, 

 except at the base ; distal joints of the hind tarsi blackish. Wings nearly hyaline ; costal cell yellow ; 

 subcostal ceU brown ; the costa with a blackish cloud distaUy. 



Length 10-11 miUim. 



Hab. Mexico, Omilteme in Guerrero 8000 feet (H. H. Smith). 

 Fifteen specimens. 



DIDEA. 



Didea, Macquart, Hist. Nat. Dipt. i. p. 508 (1834). 

 Enica, Meigen, System. Beschr. vii. p. 140 (1838). 



l. Didea laxa. 



Didea laxa, Osten Sacken, Bull. Buffalo Soc. iii. p. 66 1 ; Cat. Dipt. 2nd ed. p. 245, note 212; 

 Willist. Synopsis N.-Am. Syrphidae, p. 90, t. 4. figg. 4, 4a 2 . 



Hab. United States, New Hampshire 1 2 , Maine \ Michigan \ Washington \ 



