390 



THE MICROSCOPE. 



supply of food, and apparently without exertion on the 

 part of the creature itself. From this most marked cha- 

 racteristic, Dr. Farre was induced to give them the name 

 of Ciliobrachiata. But it has since 

 been determined by naturalists, from 

 the Bryozoa possessing a higher 

 organization than any of the pre- 

 ceding families of zoophytes, and 

 also from the presence of striped 

 muscular fibre in their bodies, to 

 transfer them, with other allied 

 genera, the Flustra, Lepralia, An- 

 guinaria spatulata, Notamia, &c., 

 to a sub-molluscan kingdom. 1 



Polyzoa are generally found 

 living together in great numbers, 

 and always clothed with hardy 

 coverings or polypidoms. They 

 subsist on small animals, and differ 

 from most other Mollusca in being 

 able to protrude themselves from 

 their cells. When the creatures 

 draw themselves within their pro- 

 tective homes, to the bottom of 

 w hi cn they are attached by a sinewy 



showing its internal struc- ,. ',, ,-,-, ,1 i 



a smaller ligament, they double themselves 



up by ben( }i n g fa Q J ower part o f 



the body upwards. It presents a 

 beautiful sight, from its blossom-like appearance and busy 

 cilia ; its protrusion and retraction are performed with 

 surprising quickness, as it has two sets of muscles for the 

 purpose, one acting on the body of the animal, the other 



(1) Mr. Gosse, in his Manual of Marine Zoology, adopts the idea, now pretty 

 general, that the Pidyzoa belong to the Molluscous division, in spite of their 

 external resemblances to Polypes, and he places them among Molluscs. In 

 this, perhaps, he has thought more of systematic views on classification, than 

 of the student's convenience. It seems to us quite clear that without adopting De 

 Blainville's principle of classifying animals according to their envelope as the 

 best principle of scientific classification, we should adopt it in works of refer- 

 ence like the present, since the external characters are necessarily those most 

 immediately recognised by the student ; and in the case of the Polyzoa, they 

 are so remarkably similar in external characteristics to the hydroid polypes, that 

 they were always classed with them, until the profounder investigations of Van 

 Beneden, Allman, and others, revealed the resemblances between the internal 

 characteristics of the Polyzoa, Bryozoa, and those of molluscs. 



Fig. 201 . BryozoaBowerban 

 kia, li BowerbanTcBryozoon 

 ng its intt 



near it 

 animal withdrawn into 

 cell. 



