1909.] LIFE-HISTORY OF THE AGRIONID DRAGONFLY, 263, 
shghtly dorsally. The rectum is the continuation of the small 
intestine and occupies almost the whole of the last four segments 
of the body. The small intestine at one time appears globular 
and at another as a thick cord of tissue, the contractions appa- 
rently commencing anteriorly and passing backwards. A. con- 
traction begun in the small intestine continues through the 
rectum, which, like the former, is sometimes a large sac and some- 
times a thick cord. With regard to the number of Malphigian 
tubules, Wheeler (1891-3) suggests that the embryonic number 
in the Odonata “will probably be found to be 4 or 6.” There 
are, however, only two in Agrion pulchellum at this stage. 
The heart consists of nine compartments and lies in the 
abdominal segments 1 to 9. Hach compartment is separated from 
the next bya pair of very distinct valves, which liein the posterior 
region of each abdominal segment. Immediately in front of each 
pair of valves is a pair of ostiain the lateral walls of the heart, so 
arranged that when the valves are open between two compart- 
ments the ostia are closed. The heart opens anteriorly into the 
dorsal vessel, or aorta, which has only a slight contractile power, 
and this vessel runs forward into the anterior region of the head, 
where the blood-stream divides into two and passes downwards in 
front of the head. 
There is at this stage no circulation in the antenne or in the 
limbs. The blood returns through the body by various lacunz. 
The two large lateral sinuses, in which at later stages the blood- 
flow is easily seen, are but little developed at present. The 
corpuscles, which are large more or less oat-shaped bodies, can be 
seen passing backwards along the “ pericardium,’ and a few can 
be seen every now and again making their way up from the 
lateral sinuses and after much oscillation entering the heart by 
some of the anterior ostia. The great majority of the corpuscles, 
however, re-enter the heart by the two large ostia situated at the 
posterior end of the 9th segment. Between these two ostia is a 
strong ligament passing back into the 10th segment. 
The ventral nervous system, so far as it is visible in the living 
nymph, consists of a large (double) ganglion in each of the 
abderminal segments 1 to 7, and between the ganglia the cord 
is double, the two parts being quite separate. Behind segment 7 
these two cords pass backwards and break up into finer nerves. 
There is no sign at this stage of any sexual armature. This 
first appears, I believe, about the 7th stage, but I have made very 
few observations on this point. 
Stage 2. 
At the first moult of the true nymph certain changes are 
visible, showing an advance in organization. . The antenne are 
now composed of 4 segments, the apical one having divided 
transversely into two of almost equal length. The labial palpi 
now each bear two long stiff incurved hairs, the second hair having 
