AQUATIC COCKROACHES. 
Or 
if the supply is entirely cut off there is practically no reserve 
supply contained in the body to draw upon. Hence the rapid 
death of the insect when totally submerged ; if only partially 
submerged death supervenes less rapidly, probably because some 
air can be drawn through the thoracic spiracles. Panesthia 
javanica is able to endure total immersion longer than the partial 
immersion to which individuals were submitted, because these 
individuals, when bound, struggled so violently as to make heavy 
demands on their reserve air-supply ; their position was so con- 
strained, so unusual, and so unnatural that they were not able 
to ‘‘take matters quietly,” even when fastened in a position 
presumably favourable to drawing in a fresh supply. Plateau 
has shown that aquatic insects drown more quickly than terres- 
trial insects, and suggests that this is because their supply 
of oxygen is quickly converted into CO, through their violent 
struggles to escape, whereas terrestrial insects, when submerged 
in water, soon cease to struggle, and, although they become 
comatose, they recover power of movement when restored to 
land. It would be of interest to learn if an aquatic insect such 
as Dytiscus would endure partial immersion, i.e. with the tip of 
the abdomen exposed, as well as the aquatic Blattids. 
Dr. Nelson Annandale discovered some aquatic Cockroaches 
in the Malay Peninsula* ; the females were wingless, and rested 
on floating logs, whence they dived into the water when dis- 
turbed ; the males were winged, and were seen to rise from the 
surface of the water, but were never seen to enter it. Dr. Annan- 
dale states, moreover, that the egg-cases of this species were 
found in crevices of the floating logs. If the Malay Peninsula 
species belongs to the same subfamily of Blattide as the Bornean 
species, namely, to the Hpilamprine, this discovery of egg-cases 
is of some interest, for the Epilamprine are, so far as is known, 
viviparous insects, the chitinous ootheca deposited by the females 
of other subfamilies being represented by a delicate membrane 
enveloping the eggs inside the brood-sac of the mother. Unfor- 
tunately, Dr. Annandale’s specimens appear to be lost, so that 
they cannot be identified with certainty. 
Another species has been discovered in Formosa,+ and Dr. 
* Ent. Rec. 1900, p. 76. 
+ Shiraki, Ann. Zoolog. Japon. vi. 1906, p. 82, pl. 2, f. 4, 
