DIPTERA. 327 
larvee inhabit cow-dung, earth, and dung-hills, and have little ranges 
of hairs on their annuli. Their pupz are not enclosed in cocoons *. 
AspistEs, Hoff., Meig. 
The only Insects of this division which have but eight joints in 
the antennee, the last forming an ovoid club fF. 
All the following Diptera, a small number excepted, have their 
antennee composed of three joints, the first of which is so short, that 
it may be excluded from the supputation; the last is annulated trans- 
versely, but without distinct divisions. Itis frequently accompanied 
with a seta, usually lateral, and situated on the summit in others, 
presenting two joints at base, sometimes simple, and sometimes 
silky. When this seta is terminal, it frequently happens that its 
length diminishes and its thickness increases, so that it has the form 
of astilet. Although this piece may be considered as a continuation 
of the antenhe, yet asitisseparated from them, and appears to con- 
stitute an appendage, to deviate from the course generally adopted, 
by adding to the ordinary number of the antennze those of the seta, 
would only disturb the harmony of our nomenclature. The palpi 
never have more than two joints. 
Some, a few excepted, whose larve divest themselves of their skin 
previous to becoming pupze, always have a sucker composed of six 
or four pieces; the proboscis, or at least its extremity, that is to say, 
its lips, is always salient. ‘The palpi, when they exist, are exterior, 
and inserted near the margin of the oval cavity, close to which arises 
the sucker. 
The larvze, even of those in which the skin forms a cocoon for the 
pupa (Stratiomis), retain their primitive form. 
This subdivision will comprise three families. 
FAMILY II. 
TANYSTOMA. 
The Diptera of this family are distinguished from those of the 
two following ones by the last joint of the antenne, which, exclusive 
of the seta which may terminate it, presents no transverse division; 
the sucker is composed of four pieces. 
Their larvee resemble long and almost cylindrical worms, with a 
constant and squamous head, always provided with hooks or retractile 
* See Meigen. 
+ Idem. 
