214 



ZOOLOGY. 



Fig. 168. Actinia; Sea- 

 Anemone. 



careous plates, called shells (Fig. 166), and this is sometimes 

 developed in its interior. In this primary division the organs 

 of the senses are almost always 

 very incomplete ; there seems to 

 be no special organism for smell, 

 and in a great number the eyes 

 are wanting : they have hardly 

 ever limbs for locomotion; and 

 finally, the blood is white as in 

 most of the annelides, but the 

 circulation is often much more 

 complete. 



377. Zoophytes. Finally, 

 in the fourth and last primary 

 division, the different parts of 

 the body, in place of being 

 grouped symmetrically with reference to a median plane, 

 tend rather to arrange themselves around a central point or 

 vertical line, so as to affect a radiated disposition more or 

 less complete. With regard to a nervous s}^stem, no trace is 

 generally to be observed, and where it exists, it is reduced to 

 a rudimentary state; the organs of the senses are also 



almost completely wanting ; 

 finally, all the parts of the 

 economy become of an ex- 

 treme simplicity. For a 

 long time they were mis- 

 taken for vegetables, and 

 hence theirnameof zoophyte 

 or animal-plants, and they 

 have been called radiated 

 animals, by reason of the 

 obvious radiated disposi- 

 tion of their organs. The 



Fig.l69.-Talitrus; Sand-hopper. polyps, of which we have 



already spoken ( 347), the 



actinise or sea-anemones (Fig. 168), and the asterias or sea- 

 star (Fig. 159), are specimens of this division. 1 * 



378. Subdivisions of the Primary Division into 

 Classes. The animals thus arranged under a primary division 



* Some zoologists admit a fifth primary division of the animal kingdom, 

 comprising sponges, and characterized by the absence of all regular form. 

 But it seems to us that this classification ought not to be adopted, for these 



