A DECADE OF AUSTRALIAN THYNNIDEOUS INSECTS. 119 
marginal line running across the back of the head; between the 
antennz is a yellow Y like mark. The clypeus is iarge, prominent, 
convex, and yellow, truncated at the tip, exposing the porrected 
semicircular and ciliated yellow labrum ; the mandibles are slender 
and yellow, with the tips brown; the maxilla and mentum are pale 
yellow—the former scarceiy ciliated; the maxillary palpi are 
rather short; the antenne are slender and filiform, measuring 
rather more than 4 lines in length. The collar is fulyous, with a 
small black spot in the middle of the anterior margin. The meso- 
notum has the lateral margins rather elevated, and the middle 
marked with a yellow spot; the scutellum also bears a yellow spot 
of like size, followed by a curved yellow lunule; and the meta- 
thorax, which is broad with the lateral angles rounded, is marked 
with two oblique yellow lines; the wing-scales are yellow, and the 
space between the scutellum and postscutellum is marked with 
yellow. The abdomen is oblong, rounded before and behind, and 
sub-depressed, of a rich orange colour, with the base and the 
incisions black; the anterior segment is channelled down the 
middle, and the terminal ventral segment is armed with a short 
acute deflexed spine, the sides of which, at the base, are dilated : 
the thorax beneath is black, clothed with silvery gray pile: and 
each side of the mesothorax and metathorax bears a yellow spot 
beneath the base of the fore-wings. The abdomen beneath is fulvous, 
fasciated with black; the legs are fulvous, with black coxe; the 
posterior pair streaked with yellow. The wings are golden yellow, 
with the stigma fulvous. 
Inhabits King George's Sound. In Mus. Westw. 
THYNNUS (AGRIOMYTA?) TRIFIDUS, Westw. 
(Plate 77, fig. 4.) 
T. gracilis, elongatus niger, capite thoraceque opacis flavo variis, abdcmine nitido segmentis 
singulis 5 basalibus lunulis duabus fiavis fasciolam nigram includentibus, pedibus obscure 
castaneis. ¢ 
Long. corp. lin. 85. Expans. alar. lin. 133. 
This species seems nearly allied to Agriomyia affinis, Guér. 
(Mag. de Zool., 1842, p. 4), but that species is too concisely 
described, and the original specimen too mutilated to allow me to 
determine its specific identity therewith. The head is obscure 
and black, and finely punctured; the eyes margined with yellow, 
except on the crown of the head: the middle of the face with a 
yellow y like mark; and the front of the head narrow, yellow, and 
with a black, trifid divergent mark. The clypeus is rather 
