250 TOMES, ON A TRICHOPTEROUS LARVA, 
to that at which it began. When the case has attained a 
certain size much shorter filaments are employed, and these 
are arranged in more open curves across the ends, thus 
lengthening the case without increasing its breadth. 
The Conferva remained green, and appeared to flourish 
perfectly in its new situation ; the separation of the filaments 
having been always at the joints, as Mr. Tuffen West pointed 
out, there were no injured cells to decompose on the larva 
case. The larve swam about easily, seemingly but little 
encumbered by the cases, which were held with the flat sides 
vertical. 
Whilst in my possession the larve manifested the most 
ceaseless activity, sorting over and biting off filaments of Con- 
ferva; after working for a time at one end, they would sud- 
denly bend upon themselves, pass down the inside of the case, 
and resume their task at the opposite end. They were, as far 
as I could tell, strictly herbivorous. Eventually the ends of 
the case were closed up, and it was attached to some stick 
or plant near the surface of the water; unfortunately, none 
of my specimens survived beyond this stage; I have, how- 
ever, found the empty cases gnawed through near one end, 
but have failed in discovering the adult form. 
There can, nevertheless, be but little doubt that this larva 
belongs to the genus Hydroptila; the case which it forms 
corresponds in essential particulars with those described by 
M. Jules Pictet,* in the following terms as peculiar to this 
genus, ‘‘ qui vivent dans les étuis applatis, en forme de rein, 
ouverts par deux fentes, composés d’une soie solide.” The 
larva does not, however, correspond exactly with any descrip- 
tion there given, nor does the case precisely resemble in form 
any there figured; that which it approaches most nearly being 
a larva the perfect form of which was not known. 
The larva of H. pulchricornis resembles that now under 
consideration in general form, and in the possession of the 
hooked caudal plate ; it differs in having scale-like append- 
ages on the 3rd, 4th, 5th, and 6th abdominal segments, in 
having shorter legs of uniform length, and in the form of its 
case, which is kidney-shaped. 
The larva of H. flavicornis bears a closer resemblance, but 
constructs a case terminated at one end by a point. 
The larva of H. Brunneicornis is not, as far as I can ascer- 
tain, certainly known. These larve are described as making 
little addition to the exterior of their silky cases besides a 
few grains of sand, which would not require any very 
* «Recherches pour servir 4 |’ Histoire et & l’Anatomie des Phryganeides,’ 
