37 



oxtendecl into a tail behind ; tlms proving tlie compound struc- 

 ture of the living corpuscle, -svliich many observers, by asserting 

 that it is absolutely homogeneoiis, liave liitherto denied. 



Plnmatclla rcpens. — Mr. FuUagar read tlie following paj)er on 

 this frosli-water polyzoon, Avliicli he illustrated by drawings and 

 living specimens : — Among the most beautiful and interesting 

 forms of invertebrate animals are those strange phytoidal pro- 

 ductions whicli, long confounded with the polypes, were at last, 

 by nearly simultaneous investigations of several naturalists, 

 separated as a distinct group, and described by Thomjison under 

 tlie name of Polyzoa, and shortly after indicated by Ehrenberg 

 under that of Bryozoa. Tliey are chieflj- inhabitants of the sea, 

 wliere they may be witnessed under numerous plant-like guises ; 

 now spreading like a lichen over submerged stones or old shells, 

 or the broad fronds of Laminaria and other sea-weeds ; now 

 forming soft, irregidar, fungus-like masses, or hard, calcareous, 

 branchy groAvths, like diminutive trees; and now again present- 

 ing the appearance of the most delicate and excj^uisitely fanned 

 sea- weed, or moss, offering, even to the unassisted eye, in the 

 endless repetition of the same element of form, objects of sur- 

 passing symmetr}' and beauty. The Polyzoa, however, are not 

 by any means exclusively cfjufined to the ocean ; and though by 

 far the greater number are marine, yet in the still and running 

 waters of the land, in the broad river and the rushing stream, in 

 the pure, cold mountain lake and stagnant waters of the moory 

 fen, species are to be found which in interest yield not one jot to 

 theii' brethren of the sea, and offer to the naturalist an inex- 

 haustible source of gratilication, in the beauty of their forms 

 and the wonders of their organization. The specimen shown 

 under the microscope is one of tlie fresh-water polyzoas, the 

 " Plumatella repens." They are \gvj beautiful objects, and 

 wore obtained from a pond in the neighbourhood of Canterbury, 

 Avhere they were growing in great profusion. I have been en- 

 abled to keej) some of them aliA-e in a small cell for more than a 

 mouth, and during that time have had ample opportunities of 

 studying a little more of their economy by the aid of the micros- 

 cope, of which, by the assistance of tlie diagram I have drawn, 

 I will endeavour to explain. In order to keeji them alive I hacl 

 to feed tliem twice a day with monads, a large quantity of which 

 I fortimately had in one of my aquariums, they were so numer- 

 ous that the water appeared of a bromi coloiu-, and so thick and 

 clouded by them that the gold fisli contained in the glass was at 

 times scarcely Aisible. The monads individually are perfectly 

 invisible to the unassisted eye. On these monads the plumateUa 

 fed greedily, and as they were reduced by the action of the 

 stomach in the process of digestion, the stomach became filled 



