1881.] Entomology. ~ 661 
depth about 14™. The spine-like process (Fig. 1, @) which 
arises from what may be termed the front of the case is of a 
dense horny nature, quite unlike the remainder of the case. It 
expands below into a hatchet-shaped plate (Fig. 1, 4). The spine 
indeed is formed by this plate narrowing and folding backwards 
above the case until its edges almost meet, thus forming a partial 
tube, which, as will be seen later, facilitates the entrance of air 
into the interior. The length of the tube, as also the shape of 
the plate, varies somewhat. Below the hatchet-shaped expansion 
is a narrow opening (Fig. I, c) into the case, allowing the water 
free passage from without and permitting the escape of the larve. 
he eggs form a discoid mass suspended from the roof of the 
nidus. They are all placed vertically and arranged closely in a 
single layer. (See Fig. 1, @.) Specimens (in alcohol) are cylindri- 
cal, about 4™™ in length and about 1™ in diameter. One hun- 
dred and seven were counted in one nidus. The mass is surrounded 
by a rather loosely woven silken coat, while each egg is wrapped 
Separately in a coat of similar character. Below, at the sides, 
and behind the mass, is left a vacant space (Fig. I, ¢) into which 
the opening in front gives access to the water. The silken material 
above and in front of the eggs is so disposed as to form large. 
cells (Fig. 1,/) and these connect with the tube through which 
air is admitted. 
The chief object of the peculiarly constructed case appears to 
be to ensure a supply of air to the newly hatched larve. As 
will be seen by reference to the figures, this object is attained by 
excluding water from, and admitting air into, the upper part of 
the case, and by attaching a float to the upper surface. This 
keeps the top of the case at the surface of the water while the 
air-tube projects above. 
In the very young larve, the head is relatively wider and larger 
‘very way than in older examples ; the body is covered by a coat 
of short, fine pubescence, becomes gradually wider from behind 
forwar ds, and the general color is a uniform grayish-brown, becom- 
Ing lighter beneath, In older examples, the body is sensibly 
natrowed before and behind. In the largest specimen examined, 
the pubescence is wanting, and there is a faint dorsal line, with 
a Droader waved line bordered outside with dark on each side 
of it. The head is so attached to the body as to project obliquely. 
upwards; it is reddish-brown, with obsolete darker shades. The 
mandibles and labium are narrowly edged with black. The legs 
are of the same color as the head. The skin is-minutely roughened 
ae deeply wrinkled. The lateral appendages of other Hydrophi- 
la are represented by elevations so slight as to be scarcely 
- i ¥ rom the under side of the last segment of the abdomen 
. 1S species, arise two light-colored, cylindrical, flexible appen- 
(eee about equal in length to the first joint of the antenna. 
or the larva, see Fig, 1, g:) 
