No. 413.] DEVELOPMENT OF THE DIPTERA. 365 
The larva of Holorusia rubiginosa! is cylindrical, worm- 
like, tapering slightly towards both ends, without feet or other 
special organs of locomotion. It attains a length of three 
inches (outstretched full-grown specimens). The head is a 
retractile, strongly chitinized capsule, with biting mouth- 
parts. The internal anatomy is simple. The musculation 
consists, except in the head, of simple segmental, longitu- 
dinal, integumental muscles and of annulate integumental 
muscles. Locomotion is a simple squirming or wriggling, 
caused by longitudinal contractions. The alimentary canal 
is a straight tube divisible into the usual parts. The ven- 
triculus has four diverticula or czca, and the large intestine 
has a single forward projecting diverticulum. There are four 
Malpighian tubules. There is a single pair of large salivary 
glands, each gland bent double. The respiratory system con- 
sists of a single pair of large spiracles situated on the posterior 
aspect of the last abdominal segment, and of a pair of main 
longitudinal tracheal trunks with their branches. The larval 
life lasts several weeks. 
The pupa is found in the same place inhabited by the larva, 
and is of simple character. It is from one and one-fourth to 
one and three-fourths inches long. There is a pair of slender, 
short respiratory tubes on the prothorax. The pupal stage 
lasts twelve days. 
In the course of the postembryonic development of Holorusia 
I have found no occurrence of phagocytosis. The breaking 
down of the muscles and salivary glands and fat body of the - 
larva (tissues in which phagocytosis most certainly occurs if 
at all and in which it is most readily determinable) is accom- 
plished apparently entirely by simple « selbständige Degen- 
eration” (Karawaiew). The breaking down of the muscles 
does not begin until after the pupal life is well started. In 
fact there is no very great breaking down essential. The 
musculation of the adult differs from hat of the larva more 
in the addition of the wing and leg muscles of the thorax 
* This is the first published reference to the immature stages of this giant 
tipu - The larve were found abundantly on the banks of a small stream near 
this university (Stanford), lying in mud and slime composed of decaying leaves. 
