WILLIAMS: HABITS OF SCUTIGERELLA. 
473 
The alimentary canal is a non-coiled tube running through the body 
with a median enlargement, the stomach, or better the mid-gut. This 
is separated from esophagus and intestine by valve-like folds as the 
diagram (text fig. A) shows (also see fig. 7, pi. 38). 
Above the alimentary canal lie the dorsal longitudinal muscles and 
the dorsal blood vessel. The location of the dorsal muscles is shown 
in figure 6 (pi. 37). 
On the sides of the intestines in the posterior part of the body lie 
the paired ovaries or the testes. The testes are said to be connected by 
one or more commissures. From the sex organ a duct passes forward 
on either side, at last uniting with its fellow from the opposite side in 
an unpaired sexual opening between the coxae of the fourth pair of 
legs. No author has yet demonstrated any secondary sexual differ¬ 
ences between the male and female though Grassi would seem to indi- 
Fig. A. 
cate, when he says that males were taken for females with undeveloped 
eggs, that the males are smaller than the females. The male organs 
are active in animals taken in October in this region. This has been 
shown by sections. 
A pair of Malpighian tubules branches off from the intestine just 
back of the mid-gut, one on either side, and passes forward. The 
fact that there is but one pair shows that the Symphyla are Diplopod- 
like and not like the Chilopods which have four Malpighian tubes, 
two on each side of the intestine. 
The spinning glands extend forward from the cerci to about the 
third segment from the last. They are modified dermal glands whose 
secretions unite to form the thread which Scutigerella spins so freely. 
In the diagram (text fig. A) the gland is shown as transparent in order 
not to obscure the intestine just behind it. 
The nervous system lies in the mid-line of the body and beneath the 
