1912] Internal Anatomy of Icerya Purchast 385 
The parent digestive cells of the ventriculus contain as many 
as five nuclei each, and there can be seen free cells in the ven- 
triculus which have been given off from the attached parent 
cells. These free cells possibly assist in digesting the food. 
The ventriculus runs back a short distance farther to about 
the junction of the sixth and seventh segments, and then turns 
abruptly and runs forward well past the junction of the cesopha- 
gus and the proventriculus. Here it makes a couple of turns, 
going backward and then forward to its junction with the 
ileum, at which point it widens out for a short distance. 
The ileum is very short and is small in diameter. The 
colon is largest at its anterior end and then, growing smaller, 
runs backward and finally merges into the rectum. The rectum 
is in the seventh abdominal segment, and the anal opening is on 
the dorsal surface of this segment. 
Salary Glands. (Plate XXVIII, fig. 2). 
The salivary glands are located on each side of the chitinized 
box of the mouthparts. There is one gland on each side, made 
up of three spherical cells, heavily nucleated. A duct, carrying 
the secretion, leads from each gland to the mouth. 
Malpighian Tubules. (Plate XXVIII, fig. 3). 
The malpighian tubules are three in number, convuluted 
and considerably longer than the intestine from its point of 
junction with the cesophagus to its most posterior point. The 
tubules are very dense, with heavily nucleated cells, and besides 
being convuluted, are curved to a certain extent at their poster- 
ior ends, and seem to be fastened to the ventriculus by a few 
very fine muscular fibres. 
RESPIRATORY SYSTEM. 
(Plate XXVIII, Fig. 7.) 
There are two pairs of spiracles, the first pair being located 
on the ventral side of the prothorax, posterior to the anterior 
pair of legs, and the second pair between the meso- and meta- 
thorax on the ventral side posterior to the middle pair of legs. 
A groove extends from each spiracle to the margin. 
Each spiracle has a somewhat kidney-shaped funnel-like 
opening, very strongly chitinized. A large trachea extends in 
from each spiracle on either side; this soon divides into three 
main trachee in the anterior system and four in the posterior 
