98 CLASSIFICATION OF THE ANIMAL KINGDOM. 



tubular Polyps spoken of before, and differ from them externally chiefly in 

 having their tentacula covered with an immense number of vibrating cilia, 

 which the latter, it will be remembered, never possess. In one of this 

 class, the Bowerbankia, which the author has taken for general illustration, 

 the digestive apparatus is very complex, consisting of a gizzard, with a 

 stomach aud intestinal apparatus. The Flustrge and Escharse have also 

 highly-developed digestive organs, though not so perfect as those of the 

 animal just described. The Bryozoee are reproduced by the growth of 

 germs of buds, and by ciliated gemmules capable of locomotion; they 

 possess also a rudimentary muscular fibre. Nothing is said about their 

 nervous system, though probably it exists; and with the exception of their 

 superior digestive apparatus and slight muscular development, they do not 

 greatly differ from the Acritous Polyps, which, in Joutward /orm, they some- 

 what resemble. They are produced in the same way, namely, by gemmules 

 external and internal, and, in this respect, are not so highly organized 

 as some of the preceding class — the Sterelmintha. 



Next in order come the Rotifer a animals, which, although they resemble 

 thg Animalcula Infusoria in the kingdom Acrita, and were long confounded 

 with them, have been lately discovered to possess a much higher structure. 

 Their organs of locomotion are rows of cilia placed round the mouth, which, 

 when in action, appear to revolve like wheels. They possess distinct muscular 

 fibre, and a digestive apparatus provided with a pharynx, a gizzard of 

 rather complex construction, and a stomach with no intestinal division; 

 and they have also a rudimentary liver. Ehrenberg thinks that he has 

 discovered a nervous system distributed through the body of these animals, 

 as well a§ vascular apparatus, but the latter at all events seems to be 

 doubtful. Their mode of respiration is probably by the introduction of 

 water within the body to bathe the viscera, and their reproductive system 

 is of a complex kind, though these animals are not dioecious; and their 

 organization in this respect, therefore, though superior to the Bryozoee, 

 must be considered inferior to the class Coelelmintha, and others we have 

 already examined. 



The Epizoa come next in order: animals which live parasitic on fishes, 

 Crustacea, etc., attaching themselves to the mouth, gills, branchiae, or other 

 exposed parts. These creatures, some of which are very singular in shape, 

 and have strange rudimentary leg-like appendages, approximate in their 

 higher types to the family of the Crustacea. They are dioecious, and their 

 digestive apparatus is very simple, consisting of an oesophagus with a straight 

 digestive canal, not divided into stomach and intestine. Their muscular 

 system is more perfect than anything we have yet met with, and they 

 possess two long filamentary nerves, which run beneath the alimentary 

 canal. These animals also, it would seem, on their first exclusion from 



