40 On the Uses of the Dorsal Vessel. (Jony, 
mediately. Their common trunks, situated below the cerebriform 
ganglion, furnish numerous branches to different parts of the head, 
then in the corcelets to the different parts of the legs. When they 
reach the thorax, these trunks throw out a branch on each side, 
which goes to receive air by the opening of the tremaer, and their 
two other principal branches go to the legs. These trachez give 
likewise branches to the muscles of the thorax, and to the pulmo- 
nary tracheee and the intestinal viscera. The same is the case in 
the abdomen. In the abdomen the arterial trachee give out on 
each side as many branches as there are stigmata, and these com- 
municate with the pulmonary trachee. ‘The direction of these 
branches is transverse, compared with the axis of the body, while 
the common trunks of these same trachee, as well as of the pul- 
monary, are parallel to the axis of the body. 
The abdominal arterial trachee furnish branches to the intestinal 
viscera and the organs of generation. They form on these parts 
very numerous networks. 
The distribution of the trachez is still more admirable in the 
mantes than in the different genera that we have hitherto studied. 
Their direction is so complicated that it is difficult to describe it, 
We shall observe, however, that the pulmonary trachee originate 
above the cerebriform ganglion by a common trunk, from which six 
principal branches proceed: two lateral, which go to the eyes; two 
inferior, for the upper lip; and two others for the antenne. From 
these branches there proceed others, which proceed to the different 
organs of the mouth. This common trunk then proceeds to the 
corcelet, always separating more and more. When it has got into 
‘that part it sends off a branch which unites with an arterial trachea. 
These two trachee, thus forming but a single one, go to the first of 
the legs, and extend to its extremity, giving off numerous branches, 
The pulmonary trachee, proceeding on in the corcelet, approach 
a little to the dorsal vessel) They then enlarge considerably oppo- 
site to the first pair of legs, sending to them a branch, which unites 
with the most external arterial branch of the tremaer. By this 
union the two trunks form only a single one, which extends to the 
extremity of the first pair of legs. The pulmonary trachee then 
approach the dorsal vessel, send it some branches, as they do like- 
wise to the muscles of the corcelet. When they have come to its 
extremity, they send out a lateral branch, which unites with the most 
external of the arterial tracheze, ‘The pulmonary trachee then become 
large, and give out at first a branch, which goes to the seeond pair 
of legs; and after having diminished in diameter, they send out 
another branch in that part. These trachez furnish likewise diffe- 
rent ramifications to the dorsal vessel, and they gradually approach 
nearer it. But when they have got as far as the first stigma they 
separate from it suddenly, forming a semicircle, which gives out a 
branch that establishes a communication with the arterial trachex 
and with the seventh stigma. From this point the pulmonary 
trachee have two principal trunks: the most internal is very wind- 
