8*2 CLASS IX. ZOOPHYTES. 



ration, the part which remains in the flesh continues alive, 

 and is quite as troublesome as the whole. Some naturalists 

 consider these worms as properly belonging to the next class. 



SECTION X. 

 Class IX, Zoophytes. 



THE class of Zoophytes is the last division of the aniina. 

 kingdom, and the lowest in the scale of the animated creation. 

 It includes an immense number of individuals but obscurely 

 arid imperfectly known, and which have but few points of re- 

 semblance and connection with one another. In general they 

 have no nervous system, no complete vascular circulation, no 

 distinct apparatus for respiration, and no sense but that of 

 feeling, and perhaps that of tasting. This is not true, how- 

 ever, without exception ; for in some instances, traces of a 

 nervous system, of a circulation, and of respiratory organs, 

 may be detected, as is particularly the case in the Echirioder- 

 mata, the first order of Zoophytes. They are covered with a 

 well-organized skin, and often with a sort of shell with points 

 or spines. They have an internal cavity, in which are lodged 

 several distinct intestines, and vessels which maintain an 

 imperfect circulation. There are also distinct organs for 

 respiration, and many filaments which probably perform im- 

 perfectly the functions of a nervous system. To this order 

 belong the sea-urchin, the common star-fish, the sea-egg, &,c. 

 They are the most perfect of Zoophytes in their structure, 

 and are endowed with a curious set of organs for the purpose 

 of motion. Their shells are pierced with a large number of 

 holes, regularly arranged, through which project the feet of 

 the animal, or rather the instruments answering the purpose 

 of feet. These are little hollow cylinders, composed of a 

 membranous substance, and ending in a kind of knob, which 

 is also hollow. They are filled with a liquid, which is fur- 

 nished to them by reservoirs situated within the body. The 

 animal at will can either lengthen these cylinders and dis- 

 tend their extremities by forcing this liquid into them, or ex- 

 haust it, and thus shorten and contract them. When it is 

 exhausted, the knob or disk is drawn into a cuplike form, and 

 thus may be firmly fixed to whatever object it is applied, like 

 a cupping-glass ; and when the liquid is again thrown into it, 

 it is again loosened. By this arrangement, which enables it 

 to fix and loosen, and at the same time to lengthen and shorten 



