Mr. Hoac's Observations on the Spongilla fluviatilis. 367 
Zooph.") thus mentions what he considered remarkable specimens : * Spongia 
vulgaris fluviatilis in aquis stagnantibus sæpè crassis crustis fundum obducit. 
Talis crustze fragmenta parvulis Phryganearum larvis, membranaceis tubulis 
in spongiosa substantia nidulantibus scatentis monstravisse mihi olim sum- 
mum apud Goettingenses Botanicum celeberr. Büttnerum memini; nec simi- 
les unquam invenire ipse potui" So one of my specimens will show how this 
Sponge is seen occasionally to fix itself and to spread upon the tube or case of 
a Caddis or Cadeworm, as related in the passage just cited. Another speci- 
men here presented is interesting from its parasitical mode of growth, because 
it has invested a moss ( Hypnum riparium, Linn.) in a very beautiful manner. 
In short, I may safely infer, from the many different substances to which I 
have noticed the Spongilla fluviatilis attached, and from the many curious 
places wherein I have observed its seedlike bodies growing, that wherever one 
of these bodies can obtain a lodgement for itself, there it increases and flou- 
rishes*, and consequently, that these bodies are in fact the true sporulest or 
ovules of the River Sponge, be it a vegetable or an animal production. 
Lastly, I beg to submit to your notice three specimens of the small fresh- 
water Polypary, named Plumatella repens by De Lamarck, which I discovered, 
for the first time I believe in England, in the month of August last among 
some patches of the Spongilla from the same rivulet. | 
Two or three of these seedlike bodies having lodged in the mouths or openings of two fluviatile 
shells that form part of the case of the caddis or larva Phryganeæ, now exhibited, clearly prove this : 
they also show how the sponge begins to be developed. 
T Having yesterday received the new number (for July 1838) of the ** Annales des Sciences Natu- 
relles," seconde série, tom. x. Zoologie, I have just perused the ** Observations sur les Eponges et en 
particulier sur la Spongille ou Eponge d'eau douce, par M. F. Dujardin." At page 9, this author, who 
is convinced of the animality of Sponges, states, Dans ces diverses parcelles vivantes, on voit des 
granules colorés en vert au printemps, grises ou jaunátres à l’arrière-saison, et que je ne puis regarder 
‘comme des organes importans, ou comme des ovules de l'Eponge." But the experiments mentioned 
in the preceding notes at page 366, will entirely refute the opinion of M. Dujardin, and prove without 
a doubt that these are in reality the reproductive bodies of the Spongilla. On the other hand, 
M. Dutrochet, in his very able “ Observations sur la Spongille rameuse (Spongilla ramosa, Lam., 
Ephydatia lacustris, Lamour.," Spongia lacustris, Linn.), and in which he advocates the vegetability 
of that species of Sponge, adds concerning its seed-like bodies, ‘Ces corps sont donc des espéces 
de tubercules, ce sont des réservoirs de matière nutritive pour servir au développement du végétal, 
et à sa reproduction au printemps." See Annales des Sciences Naturelles, tom. xv. p. 212, 1828,— 
J. H., December 19, 1838. | E | 
VOL. XVIII. 3c 
