816 General Notes. [ October, 
tually attached to the anterior part of the egg-case, its attach- 
ment to the outer bag being so slight as to admit of the frontal 
rent (Fig. 2, é). 
The young larve generally break through the back part of the 
egg-case proper and remain for a day or two, and until they have 
visibly increased in size, within the outer bag, issuing finally 
through the frontal rent through which the water is easily admitted. 
When floating freely the floater is always mostly out of water, the 
point upward and obliquing slightly forward. The eggs are thus 
bathed in water but freely aérated. The spike seems to be essen- 
tial to their well-being, as Mr. A. G. Laker! found that those of 
H. piceus failed to hatch when it was cut off, yet the somewhat 
similar case of the common Aydrobius fuscipes has no such 
point, but in its place the silk is extended from beneath the leaf 
to which the case is attached to the upper surface over which it 1s 
spread, and according to Mr. Laker they will hatch if kept en- 
tirely under water. ee 
We conclude that the curious contrivance in Hydrophilus 1s 
intended not only to secure an ample supply of air to the eggs 
and to protect them, but also to protect the newly hatched young 
from their numerous enemies until their jaws have strengthened 
and they are better able to begin the struggle for existence. 
We have often been curious to know whether or not the sternal 
spine of the bectle was used to form the point of the floater. It 
seems useful for such a purpose and yet occurs in both sexes. I 
the first one had gone through its transformations, and issued a5 
a beetle. The molt takes place in all sorts of situations, and ern 
while the larva is floating on the surface of the water. he color 
becomes paler toward each molt but dark afterwards, the rae 
teristic dark and sordid-white mottlings, especially the wavy wis 
along the back, being most conspicuous just after the molt. They 
fed on everything with which they came in contact, as ~— 
Ephemerid and Libellulid larve, other aquatic animals, and eve 
raw beef which we gave them. lled 
The pupa, which was readily formed in a large flower pot fille 
1 The Entomologist (London, Eng.), XIV, p. 83. 
