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 lieen 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 Linnsean Transactions ; and that circumstances have as yet 

 prevented me from procuring more of these anomalous insects, so 

 as to determine whether they be only Larva, 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, 



John Hogg. 



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. — Edward Forbes. 



