Miscellaneous. 315 



alternate leaflets, which are only found on the apical flower ; but in 



their place in the other there are sometimes three bracteae, placed 



far from each other on the peduncle, the larger one (which alone is 



constantly found) being placed at the base, where it springs from 



the scape. The flower opens regularly from the bottom upwards till 



within a few of the top ; then the top one opens, and after that the f JgfL/0^ 



remaining ones which surround its base. *^ \^^ 



RIVER-SPONGE INSECT. 



Correction of a mistake relating to the River-Sponge Insect, and to 

 the Freshwater Sponge. By John Hogg, Esq., M.A., F.R.S., 

 F.L.S., &c. 



To the Editors of the Annals and Magazine of Natural History. 



Gentlemen, — Having forgotten to correct an error into which 

 the able Entomologist, who contributed the description of the ano- 

 malous Insect discovered by myself inhabiting the Spongilla fluviatilis, 

 to the * Magazine of Natural History,' had inadvertently fallen, in 

 making me conclude that the motions of that Insect were mistaken 

 by some French naturalists for the movements of the Freshwater 

 Sponge itself, and having lately read the same error inserted in the 

 ' Annales des Sciences Naturelles,' I think it incumbent on me no 

 longer to delay sending you the following correction, which I hope 

 you will favour me with publishing in an early Number of your ' An- 

 nals and Magazine of Natural History.' 



The mistake, which I here point out, is contained in this para- 

 graph, taken from p. 200 of the ■ Magazine of Natural History,' 

 vol. iii. New Series; — "Mr. Hogg, F.L.S., by whom these insects 

 were discovered, during a series of minute investigations upon the 

 Spongilla, has arrived at the conclusion that the motions of these in- 

 sects, and the undulations which they produce in the water, have 

 been mistaken by Laurenti and others for movements of the Sponge 

 itself, and which they have accordingly regarded as affording proofs 

 of the animality of that substance." 



Again, I find the same translated into p. 380 of the ' Annales des 

 Sciences Naturelles,' Seconde Se>ie, torn. xi. Zoologie, in the fol- 

 lowing words : — " M. Hogg, qui a decouvert ces insectes pendant 

 une serie d'observations dedicates, qu'il avait entreprises sur la Spon- 

 gille, est arrive a conclure que ce sont les mouvemens de ces insectes 

 et les ondulations qu'ils produisent dans les eaux, qui ont et^ pris 

 par Laurenti et autres pour les mouvemens de la Spongille elle- 

 meme, et regardees comme des preuves de l'animalite de cette sub- 

 stance." 



Now, as well from this paragraph, as from its translation, it must 

 not only be inferred, that the same remarkable insects were actually 

 present in those specimens of the Spongilla, whilst M. Laurent and 

 others were witnessing the movements described by them, and that 

 they had not noticed the insects themselves ; but also, that the un- 

 dulations in the water or currents were produced by the respiratory 

 motions of these identical insects alone, and of no other parasitical 



