34 Journal of the Asiatic Society of Bengal. [N.S., XIX, 
pair of legs, to the third pair of legs, and four small fine nerves 
to the first four abdominal segments. 
Respiratory System.—This differs in several important 
points from the usual type found in insects. In both sexes there 
are ten pairs of functional spiracles in the pleura of the body 
segments—two in the thorax and eight on the first eight abdo- 
minal segments. But in the female there is, in addition, one 
degenerate spiracle on the ninth segment which has lost its con- 
nection with a trachea and whose opening has been obliterated. 
Thus, in both male and the female, the ultimate and the penulti- 
mate abdominal segments are devoid of spiracles due to teles- 
coping of these segments. 
The thoracic spiracles are comparatively large oval open- 
ings with their rims highly chitinized and thickened. They are 
situated between the prothorax and mesothorax, and between 
the latter and metathorax. The second spiracle is regarded as 
belonging to the metathorax, the first is believed to be protho- 
racic by some authors, e.g, Davidson (5) and Grove and 
margin of the mesopleuron and is covered by the ES 
propleuron. 
An abdominal spiracle is present in the antero-dorsal corner 
of each segment, as a small circular opening with thick black 
rims. Unlike a vee anicadie it has no valve or any other 
closing apparatu 
short pee trachea arises directly from each thoracic 
spiracle in the abdomen; the trachea commences from a diver- 
ticulum at the base of the spiracle (Fig. 17b). According to 
Murray, this diverticulum compensates for the absence of a 
closing apparatus since it renders difficult the passage of foreign 
bodies inside. 
trachea, after its origin, divides into a dorsal and a ven- 
tral branch which give rise to well defined dorsal and ventral 
systems. 
The dorsal tracheal system (Fig. 17a, right side of the dia- 
gram): The branches of the dorsal tracheal arm bifurcate after 
passing some distance inwards. Jn the prothorax this division 
occurs at the very base and thus two dorsal branches are seen 
to arise from the spiracle. The dorsal branches unite to form 
a continuous longitudinal trunk lying on each side of the dorsal 
median line from the first thoracic to the eighth abdominal seg- 
ment. From these trunks several small branches are given off 
to the neighbouring organs. The minor branches of one 
tracheal trunk are not connected with those of the other, except 
in the last abdominal segment where a transverse connective 
is formed by the union — the posterior branches of the eighth 
pair of dorsal trac 
While the Siaiinations of the dorsal trunk in the abdo- 




