156 MR. LUBBOCK ON TWO AQUATIC HYMENOPTERA. 
by him belongs to the same species. It is a very curious coincidence that, after 
remaining so long unnoticed, this little insect should thus be found, almost simul- 
taneously, by two independent observers. 
Perhaps this may, in part at least, be accounted for by supposing that the insect was 
unusually abundant this summer. Yet Mr. Duchess appears to have met with only one 
specimen. Mine were altogether twenty-one in number, and the females were more than 
twice as numerous as the males. 
Specimens which I forwarded to my friend Mr. Walker, to whose ready kindness and 
valuable assistance I am much indebted, were at first considered by him to be the ` 
Polynema fuscipes of Haliday, and under this name I exhibited them at the September 
Meeting of the Entomological Society. 
Subsequent examination, however, has shown that my insect, although allied to 
Polynema fuscipes, cannot be referred to that species. The males not only differ in 
colour, but also in the number of segments of the antenna, which, in my specimens, 8 
in Anaphes (the abdomen of which last is, however, subsessile), are twelve in number, 
while the males of Polynema fuscipes, and, indeed, of all the hitherto described species of 
that genus, have thirteen. 
Polynema ovulorum has been bred from the eggs of the common Cabbage Butterfly, 
and the whole group is, in its larval state, parasitic. My specimens were no doubt in 
quest of some aquatic victim ; but this can hardly have been their only object, for the 
males enter the water as readily as do the females. 
The second species to which I am anxious to call your attention is also very interesting, 
but, although apparently forming a new genus, it is in some respects less remarkable 
than the first. I found them in the same pond; but whereas Polynema natans swims 
with its wings, and uses its legs apparently only for walking, the present species, when 
under water, holds its wings motionless, and uses its legs as oars. "Though they are 
neither flattened nor provided with any well-developed fringe of setze, still they seem to 
serve their purpose pretty well, and the motion of this species is more rapid than that of 
the former. 
Both species are fond of creeping along the sides of the vessel in which they are kept, 
or on the leaves and stems of aquatic plants ; but very frequently they quit their support, 
and swim boldly out into the open water. 
As the motion in Polynema natans is caused by the wings, it might almost be called a 
flight ; owing, however, to the density of the medium, and partly perhaps to the direction 
m which the wings act, the movement, though not inelegant, is slow, and is rather a suc- 
cession of jerks than a continuous progression. | 
E € 2 geret with tracheæ, and respiration appears to take place through 
Cop dri = Most of those insect-larvæ which spend much of their 
سوسوي‎ EEE er provided with gills, or carry down with them a supply air 
possesses neither of A ak مسي‎ is is ا‎ e ie 
enero aE > ; nor can much oe take place through ti 
Moreover, it i : : 
ver, it has some difficulty in passing from air to water, or vice versá: a bubble 
