42 Tachinidae. 



there is a row of more or less developed oral bristles. On the back 

 of the head there is along the eye-margin a row of postocular bristles; 

 otherwise the back of the head is generally densely covered with 

 more or less long, pale hairs, but sometimes there are one or more 

 rovvs of black hairs behind the postocular bristles; in some cases the 

 hairs are all black. Generally there is above a pair of postocellar 

 (inner postvertical) and occipital (outer postvertical) bristles, they 

 are sometimes indistinct, especially the postocellar may be slightly 

 individualised among the hairs on and behind the ocellar triangle. 

 The orbits are generally fmely haired, the frontal stripe bare. The 

 cheeks may be bare or more or less haired, or they may bear bristles, 

 and these alternatives have systematic value. Finally the jowls are 

 generally haired with more or less strong hairs, rarely more slightly 

 haired or bare^. The eyes may be of rather various size; they are 

 bare or hairy; the facets sometimes a little enlarged towards inner 

 margin or in upper half in male or in both sexes. The antennæ are 

 inserted at the middle of the eye to considerably above or below; 

 they are generally inserted near to each other, rarely a little distant; 

 they consist of six joints the arista being three-jointed; they are of 

 common Muscid type; the first joint small, the second likewise or 

 somewhat longer, the third of various length, from as long as to 

 about six times as long as second, often relatively longer in male than 

 in female, sometimes considerably; in a couple of genera the second 

 joint is elongated and longer than third; the third joint is thus in 

 all of a shape from nearly square to elongated linear; only in one 

 Danish species {Actia fissicornis) the third joint is in the male cleft 

 in the whole length and two-branched, but this shape is found in a 

 number of foreign Tachinids, the so-called fissicorn Tachinids. The 

 arista is inserted dorsally at the base of third joint, it has the basal 

 joint quite short, often not to be seen without preparation, rarely 

 it is somewhat long (Actia)] the second joint is likewise short or a 

 little or more elongated, in some cases it is much elongated to fully 

 as long as third, and the arista then sometimes geniculate. The arista 

 is tapering outwards, the thicker basal part may be quite short, or 



1 For the understanding of this latter I must explain the following: the chitinised 

 jowl as a part stretching forwards from occiput has ahvays hairs; when this 

 part is large the jowl is quite haired, but sometimes the above mentioned 

 bare intermediate triangle is much extended and more or less displaces the 

 chitinised part, and thus the jowl, understood as the space below thé eye, 

 gets more or less slightly haired to quite bare. 



