A DECADE OF AUSTRALIAN THYNNIDEOUS INSECTS. 123 
4 lines long); the maxille are small, with the apical lobe rounded 
and homogeneous (fig. 5 c,) with the sides clothed with long hairs, 
and the palpi very long and slender, the basal joint being the 
shortest and the third the broadest. The mentum (fig. 5d, 5.) 
is narrow (with the labium inflexed), the extremity furnished with 
a very long curved pencil of hairs (scarcely shorter than the 
maxillary palpi), and the labial palpi are elbowed at the tip of the 
first long joint, which is also furnished with a long diverging bush 
of hairs; the sides of the head are furnished with long fulvous 
hairs directed backwards. The collar is but slightly developed, with 
two minute transverse yellow spots in front ; the mesothorax has its 
upper surface marked with four longitudinal channels ; the scutellum 
bears a yellow spot, followed by a transverse yellow lunate spot ; the 
metathorax is oval, attenuated behind, nearly polished, slightly 
setose ; the abdomen is rather long, depressed, and narrowed 
in front, the basal joint triangular, convex above, channelled down 
the middle ; the base black, the extremity of the remainder of the 
abdomen of a fulvous castaneous colour, slightly clothed with 
fulvous hairs, the terminal segment is carinated beneath, tridentate 
at the tip, the middle tooth being the longest and black at the tip. 
The coxe and trochanters are black, and the legs fulvous 
castaneous. Wings almost hyaline, with black veins and stigma. 
Inhabits Van Diemen’s Land. In Mus. Westw. 
I am indebted to R. H. Lewis, Esq., for this interesting insect. 
M. Guérin has described another Australian species, allied to 
the preceding, under the name of Agriomyia spinolz, with the 
observation that they differ from the rest of the genus, in their longer 
antenne, and the long hairs at the sides of the head, so that they 
*‘ pourraient bien devenir types d’un nouveau genre,” for which he 
proposes the name of Tachynomyia, which, both on account of its 
want of priority in date and its insufficient characters must be 
rejected in favour of the name Aelurus. 
The plant represented in plate 76 is Solanum stelligerum, and 
that in plate 77 is the Orchidaceous Arethusa catenata. 
Obs.—The curious structure of the anterior cox of T. inter- 
ruptus having induced me to examine the same part in other 
species, | have found that the male of T. (Thynnoides) fumi- 
pennis, (ante, p. 108), possesses a singularity of structure which 
