316 Miscellaneous. 
animals; or, in a word, that there is a necessary connexion be- 
tween the River-Sponge Insect and every species of the Freshwater 
Sponge wherein such movements and currents are perceptible. This, 
however, is incorrect ; and for the erroneous paragraph before given, 
I beg to substitute the following correction :— 
Mr. J. Hogg, F.L.S., by whom these insects were discovered, du- 
ring a series of minute investigations, by which he has become con- 
vinced of the vegetable nature of the Spongilla fluviatilis, has arrived 
at the conclusion, that the currents observable entering into and re- 
turning out of the Spongilla, and which have been erroneously ac- 
counted by some naturalists as proofs decisive of the animality of 
that substance, are caused by the function of respiration being ef- 
fected by this insect by means of its rapidly vibrating its abdominal 
filaments, or gill-like organs, within the pores or canals of the 
Sponge, and thereby producing streams in the water; for he has 
never witnessed the like currents to occur in any part of that Sponge 
which has been entirely free from that parasite. Mr. J. Hogg, 
therefore, considers, that the process of respiration being carried on 
by that or some other aquatic or marine insect, or molluscous, or 
crustaceous, animal, &c. parasitically inhabiting and almost con- 
stantly discoverable lurking within every specimen of all kinds of 
Sponge, is the principal—if not the sole—cause of the currents of 
water taking place in those most singular productions. 
I will here only remark, that this subject is fully investigated in 
my ‘ Observations on the Sponges,’ published in part 3. vol. xviii. 
of the Linnean Transactions ; and that circumstances have as yet 
prevented me from procuring more of these anomalous insects, so 
as to determine whether they be only Larve, or insects having as- 
sumed their perfect form; but, I may add, that I am still most in- 
clined to the latter opinion. 
I remain, Gentlemen, yours very truly, 
Joun Hoge. 
London, Nov. 16, 1840. 
THE ANIMAL OF HYRIA. 
The mantle lobes of the species of this genus, brought from British 
Guiana by Mr. Schomburgk, are united together behind, and fur- 
nished with two short separate contractile siphons, like the animals 
of Iridina and Leila, though the submarginal impression of the shell 
does not show indications of any inflection behind.—J. E. Gray. 
LOTTIA PULCHELLA, 
I this summer examined many living specimens of my Patella 
pulchella, and found the animal a true Lottia, thereby confirming 
its distinctness from Patella tessulata, from small specimens of which 
the shell can scarcely be distinguished. On examining microscopi- 
cally the Lottia testudinalis, I found the mantle as well as the gill 
to be covered with vibratile cilia.—Epwarp Forszs. 
