and Plants confounded with them. 205 



the joints. Schweigger states, that he found parallel fila- 

 ments in the C rubens ; but this appears to have arisen from 

 his not removing the calcareous matter completely. The 

 little seeds or grains approach the Coralline zonaria ; but 

 the external form is very different ; the frond of the latter 

 being without distinct articulations, and destitute of cal- 

 careous deposit. The parts which contain the seeds in 

 Zonaria are placed in concentric zones, as in the corallines ; 

 they are ranged in concentric lines. The body consists of 

 more distinct cells than in Corallines. 



The Zonaria squamaria undoubtedly belongs to the genus 

 Zonaria. Its consistence is greater and more like that of 

 the Fuci. Schweigger has remarked, that at a certain age 

 the Z squamaria is covered with calcareous matter, and is 

 changed into Millepora coriacea, Linn. 



3. The Zonaria form the third family, and Zonaria is the 

 only genus belonging to it. 



4. The fourth family is that of the Spongodiae. Ten or 

 twelve years have elapsed since Link observed the distinct 

 sporules of the Spongia lacustris, (Spongilla lacustris Lam 

 Ephydatea Lamx), and annually has collected them near the 

 town of Spandau. They are about the size of millet seed, very 

 visible to the naked eye. They are distinctly not parasitical, 

 and are of a yellowish colour. When magnified, they ap- 

 pear as seed immersed in a soft matter, which rests on a 

 membrane consisting of fine tubes. The Spongia officinalis 

 possesses a similar structure, as well as the & lacunidosa, 

 virgultosa and dichotoma. 



Ehrenberg has observed sporules in several sponges from 

 the Red Sea. 



Dr. Grant detected a motion in the water which pro- 

 ceeded from the apertures placed at the surface, without any 

 accompanying contraction. At the same time membranous 

 matter was discharged, which he took to be the excrement 

 of the animal. This appeared, however, only accidental, 

 and Link is inclined to consider the motion of the water as 

 similar to that in the Chara. In the Spongia panicea Dr. 

 Grant observed eggs which possessed a peculiar motion, 

 like those of the Gorgons. Link says that the Alcyonium 

 paniceum is found on the coast of England, but not the 

 S panicea, which is quite unknown to him. But even if 



