201 
tion at the bases of the hooks serves as support for an area of 
the integument, which is provided with rows of minute spines; the 
spaces between the rows form a kind of channels along which the 
food runs to the mouth. In the third stage the shape of the mouth- 
hooks are not different from those of the larvæ of other Muscidæ, 
but the integument on each side of the mouth opening is provided 
with some strong spines, and as in the second stage with rows of 
minute spines"). 
In the following I shall give a more full description of the 
larva. The shape is the usual maggot-like, tapering from be- 
hind towards the head; the number of segments is 12, correspon- 
ding with the number I have found also in the cases of other 
Muscidæ. 
First stage: The larvæ examined in this stage measured 
from 1,5—1,75 mm; they were not quite newly hatched, as they 
had almost penetrated into the skin of the bird. The segments, 
except the head, are provided with spines, which are spread over the 
whole of the segments, a little more numerous on the dorsal than 
on the ventral side, which is especially the case on the last seg- 
ments. The spines are pointing backwards with exception of those 
on the posterior margins of the segments 5—11, which are poin- 
ting forwards, and this is also the case with the spines on the 12th 
segment. The head is forwardly produced into two lobes, each 
bearing at the top a pointed optical tubercle which is almost 3 times 
longer than broad; at the side of the tubercle is found a short sen- 
Sory hair and on the ventral side some few minute sensory fa- 
cettes. The mouth hooks have a broad base; the end is provided 
with a sharp tooth, under which are found four other teeth; the hooks 
1) In the larva of Eæorista blepharipoda B. & B. I have formerly found 
a similar mouth-armature; in the second stage the end of the mouth- 
hooks is divided into a number of pointed teeths and on the side of 
the mouth opening is found both in the second and the third stages 
some sharp spines (J. C. Nielsen: Undersøgelser over entoparasitiske 
Muscidelarver hos Arthropoder. — Vid. Medd. Naturh. Forening Køben- 
havn, Bd. 68, 1911, pag. 1). 
