266 
surface. 
The salivary glands are a pair of long 
straight, flat ribbons, arising from each 
side of the anterior extremity of the 
and extending backward 
along the alimentary canal; they are 
4.75 mm. long, tapering slightly and 
regularly to a bluntly rounded tip, being 
0.54 mm. broad near the base and 0.14 
mm. broad close to the tip; they resem- 
ble flattened, braided cords, being com- 
pressed along the median line, while 
each side is regularly and deeply excised 
at frequent intervals, producing bead- 
like lateral prominences. 
The malpighian vessels originate as 
slender tubes, one on each side of the 
middle of the anterior half of the intes- 
tine; the tube gradually enlarges, and 
at a distance of 2 mm. from the origin 
subdivides into three branches (the un- 
der branch originating just before the 
other two), which are strongly waved or 
crenulated cords, and are, throughout, 
nearly or quite as large as the tube at 
its very origin; the under branch passes 
forward in a tortuous course, above the 
nervous cord, along and in contact with 
the under outer surface of the stomach, 
as far as the middle of the first abdom- 
oesophagus 
inal segment, where it bends upon itself 
and returns in a similar manner, a 
little higher up, to the point from which 
it started; the two other branches, 
which are a little smaller than the first, 
extend forward and then backward in 
a similar manner, one passing along the 
upper outer portion of the stomach as 
far as the second abdominal segment, 
and then returning, the other along the 
side of the stomach to the middle of the 
PSPC HE. 
first abdominal segment ; all three branch- 
es pass outside the tracheal tubes which 
invest the stomach, and when each has 
returned to the point from which it 
started, the extremities of the three 
threads are collected with those of the 
opposite side, in a single intricate and 
convoluted mass enveloping the intes- 
tine, and covering also the whole surface 
of the colon with their more delicate 
terminal threads. When the posterior 
part of the alimentary canal is pressed, 
whitish particles can be seen to move in 
an irregular manner within the malpi- 
ghian vessels. 
Respiratory System. The tracheae of 
the first abdominal segment are larger 
and branch more extensively than those 
of any other segment, their ramifications 
extending to the anterior extremity of 
the stomach; while those of the third 
thoracic segment are small and compar- 
atively inconspicuous and are connected 
with those of the first abdominal seg- 
ment by only a small longitudinal canal ; 
the first thoracic segment bears, however, 
an extensive bunch of tracheae, which is 
connected with that of the first abdomin- 
al segment by a long longitudinal canal, 
as large as many of the main branches 
of these two segments. 
The anterior branch of this bunch in 
the first thoracic segment supplies the 
head; it passes upward on each side 
along the hinder edge of the head, 
until it meets that of the opposite 
side, when the two join so strongly that 
considerable force is required to part 
them; and the only mark of separation 
is a pale line on the dusky surface. As 
soon as they meet they bend toward the 
