PLUMATELLA. 129 



Plumatella, I have never observed that any of them were seized, retained, 

 or swallowed. 



Numbers of the Vorticella rotatoria infest the Plumatella in Blackhall 

 pond. Many seat themselves on the extremity of the tubes, the spot 

 where they harbour in particular, and there twelve or twenty may be seen 

 at once. 



In as far as I could determine, no vegetable substance bore this zoo- 

 phyte in that pond, during the period of my investigations ; nor, with the 

 following exception, any other substance than stone, and then chiefly the 

 under surface. 



But, I was surprised to find at least four or five specimens vegetating 

 luxuriantly, inside an old tin pan, which had been thrown into the water. 

 These run over the surface of the metal in lateral adhesion, the tubular 

 receptacles of the hydrse projecting about two lines from the branch, in- 

 dependent of the hydras themselves. Whether the twigs were in adhe- 

 sion or free, they originated from only one side of the member sustaining 

 them. The best of the specimens extended two inches, or two and a half 

 in length, diverging about as much across. 



Besides all the preceding, I shall name but one other specimen in- 

 vesting a leaf of the common yellow Iris in Foulden pond after the middle 

 of September. It consisted of irregular tubular ramifications, extending 

 in adhesion about two inches. The hydra; were in such vast profusion, 

 that the formation of the specimen became more obscure with the diffu- 

 sion of the parts.— Plate XXXII. fig. 8. 



I could not ascertain that any of these animals had above 50 tenta- 

 cula in the arrangement of a crescent, like those of the rest. They were 

 of pale green colour, and presented the wonted peculiarities of structure 

 and habits, fig. 9. But owing to their particular position, and the multi- 

 tude crowded together on the edge of the leaf, where most accessible to 

 the microscope, it proved, nevertheless, impossible to free any one from 

 the rest for distinct and satisfactory inspection. The whole product had 

 a yellowish tinge. 



Perpetuation. — Some of the most remarkable facts continue to be 



VOL. II. R 



