ONCODES.-— PIALEOIDEA. 165 



Face, vertical triangle, occiput, and antennae black ; thorax of the usual brownish- 

 black, metallescent colour, with a dense, short, yellowish pubescence. Humeral and 

 prsescutellar callosities and upper part of the pleurae brownish-yellow ; above the coxae 

 the pleurae are black, shining. Legs yellowish-brown, including the front coxae ; extreme 

 base of the latter black ; tarsi brownish ; ungues and pulvilli black. Tegulae honey- 

 coloured, without any perceptible darker margin. Halteres with a brown knob. 

 Abdomen brown, the hind margins of the segments white. Venter whitish-yellow; 

 incisures darker. Wings subhyaline ; very slightly tinged with brownish before the 

 apex, near the costa ; auxiliary and first veins brownish ; the costa, beyond the junction 

 of the auxiliary vein, is dark brown and a little stouter. A single male. 



Among the described North-American species, 0. incultus, O. S., alone has the humeri 

 of a paler colour than the thorax ; but it is easily distinguished by its large size, its 

 brownish wings, &c. 



PIALEOIDEA. 



Pialeoidea, Westwood, Trans. Ent. Soc. London, 1876, p. 514. 



l. Pialeoidea metallica, sp. n., $ . 



Thorax metallic green ; abdomen brown, shining, the segments with paler hind margins ; legs reddish-yellow ; 



wings brownish. 

 Length 5-6 millim. 



Hab. Guatemala, Antigua (Stoll). 



The third joint of the antennae is broken, and for this reason I cannot refer the 

 species to the genus Pialeoidea, Westwood (loc. eit. t. 6. f. 3), with certainty. The head 

 is remarkably small, the eyes separated by a narrow front, and the wings very nearly 

 like those figured by Westwood ; the scutellum is rather broad ; but there are three 

 instead of two ocelli ; and the occiput is very much developed (like I. e. fig. 3 a), and if 

 seen from the side it occupies one half of the breadth of the head (different therefore 

 from I. c. fig. 3 b). The venation differs from I. c. fig. 3 c in the following principal 

 points : the second basal cell is connected with the margin of the wing by a vein running 

 between the fifth posterior cell and the anal cell (in the figure quoted this vein is 

 omitted, and these cells coalescent ; is not this omission accidental ?) ; the fourth posterior 

 cell is not in contact with the second basal cell ; and the second submarginal cell is of 

 a different shape, e. g. longer and broader at the base. 



The vertical triangle is large, somewhat protuberant ; the ocelli equidistant. The 

 eyes pubescent; beneath the vertical triangle approximate but without coming in 

 contact; below the antennae almost touching. The antennae are inserted in the 

 middle of the head, within a space formed by an emargination of the eyes ; their basal 

 joints in close contact. Proboscis short. 



Head black; basal joints of the antennae yellowish-brown; vertical triangle greenish 



