52 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
surface, almost covered by the second segment, two spiracles, on either side, are 
seen with a low power as small brown spots. Two black hooks or ten tacula protrude 
from the apex of this segment. They are curved towards the ventral surface of the 
maggot. The apex of each hook is blunt, and its base surrounded by a fleshy ring. 
Between them is the oral orifice. The tentacular processes are continued for some 
distance into the body of the maggot as black chitinous structures with expanded 
bases. There is probably, as in Oestrus ovis (Linn.), an articulation between the 
external and internal chitinous structures, since the arrangement of the mouth parts 
seems to be the same as in the maggot of that fly. Paired groups of minute spicular 
teeth are placed around the two tentacula so as to form a sort of cupping instrument. 
The arrangement of these teeth is as follows : — A rather large tubercle is situated on 
either side ot and above the tentacula ; each is mounted by two or more groups of 
very small chitinous teeth. Just above each tentaculum is another small group of 
teeth. On either side of these black tentacula two irregular rows of small teeth are 
placed one above the other. The two latter groups are not placed upon tubercles. 
The integument of the larva is thick and difficult to tear. The larva is able to 
withstand a good deal of pressure without injury. 
The following gross internal anatomical structures have at present been made 
out — intestinal canal, salivary gland, nervous system, and fat body. The intestinal 
canal commences as a short oesophagus, which ends in a proventriculus. A 
remarkable dorsal diverticulum, corresponding to the food reservoir of the muscid 
larvae, opens into the oesophagus near its anterior end. After the maggot has fed, 
the diverticulum is a very conspicuous object, since it is seen through the semi- 
transparent body wall as a bright red area when full of blood, extending from the 
head to about the fifth segment. The caeca, behind the proventriculus, have not as 
yet been well made out. The mid-intestine or chyle stomach is short, when 
compared with the hind intestine, and extends from the proventriculus to the junction 
of the urinary tubules with the gut. It lies in one or two coils. The hind intestine 
is very much coiled, and occupies the greatest part of the body cavity. 
The urinary tubules are lour in number, two on either side of the intestine. 
Each lateral pair combines to form a broad plate, from which is given off a single 
process for attachment to the gut. 
Each salivary gland of the larvae consists of one very long acinus made up of 
large granular cells. The gland ends in a chitinous ringed duct, which joins its 
fellow of the opposite side to form a common duct, opening near the base of the 
free portion of the tentacula. The body ot the maggot is lined by a white, loosely 
reticulated fat body. The minute anatomy ot the mouth parts and sucking apparatus 
has not been studied. 
The time required for the maturation of the larva is not yet known. The 
puparium is a dark-brown or black, cylindrical, segmented body, measuring 9-10*5 mm. 
