8 ON CLASSIFICATION. 



1. Bryozoa, or Polyps, with ciliated arms. 



2. Rotifera. 



3. Epizoa. 



4. Cavitary Entozoa or Ccelelmintha. 



5. Echinodermata. 



The reader will perceive, that this division, however well sepa- 

 rated from the preceding by physiological characters, is, in a 

 zoological point of view, principally composed of groups detached 

 from the members of other orders. The Bryozoa are evidently 

 dismemberments of the family of Polyps, from which they differ in 

 their more elaborate internal organization. The Coelelmintha are 

 more perfect forms of the Parenchymatous Entozoa. The Roti- 

 fera, formerly confounded with the Infusoria, exhibit manifest 

 analogies with the articulated Crustaceans, as in fact do the 

 Epizoa. The Echinodermata alone appear to form an isolated 

 group, properly belonging to the division under consideration. 



Third Division. HOMOGANGLIATA (Owen) ; Articulata (Cu- 

 vier)*; Annulosa (Macleay) ; Diploneura (Grant). ~f* 



(10.) The articulated division of the animal kingdom is charac- 

 terized by a nervous system, much superior in developement to that 

 possessed by the two preceding, indicated by the superior propor- 

 tionate size which the ganglionic centres bear to the nerves which 

 emanate from them. The presence of these central masses of neurine, 

 admits of the possession of external senses of a higher class than could 

 be expected among the Acrita or Nematoneura, and gives rise to 

 a concentration of nervous power, which allows of the existence of 

 external limbs of various kinds, and of a complex muscular system 

 capable of great energy and power of action. 



The nervous centres are arranged in two parallel lines along the 

 whole length of the body, forming a series of double ganglia or 

 brains, belonging apparently to the individual segments of which 

 the animal is composed. The anterior pair placed invariably in 

 the head above the oesophagus, and consequently upon the dorsal 

 aspect of the body, seems more immediately appropriated to the 

 higher senses, supplying nerves to the antennae, or more special in- 

 struments of touch, to the eyes, which now manifest much com- 

 plexity of structure, to the auditory apparatus where such exists, 



* The Cirripecla are excluded from the Articulata of Cuvier. 



-f- The Entozoa and Rotifera are included in the Diploneura of Dr. Grant. 



