10 



BRANCH CCELENTERATA. 



FIG. 14. 



BRANCH CCELENTERATA 



THE CORALS (kor'alz), ETC. 



We now meet, for the first time, with animals pro- 

 vided with a true mouth; with a skin formed by layers 

 of interlocking cells ; and with arms, or tentacles, for 

 thrusting captured food through the mouth and into a 

 central bag, which answers for a stomach. This "stom- 

 ach" is of such a rudimentary nature that it has given 

 the name (hidden intestine) to the Branch. 



The exterior of the body of COE- 

 LENTERATES (se lent'er atz) is be- 

 set with a countless multitude of 

 cells, lasso-cells, which are capable of 

 throwing out, with considerable force, 

 long threads, the fine poisoned ends 

 of which enter the skin of such ani- 

 mals as may be passing by, produc- 

 m ~ a para iy s i s an d rendering their 



capture easy. 



These animals are all aquatic : 

 many are of considerable size, and others, the Corals, 

 though often small as individuals, have been active agents 

 in changing the outlines of coasts and in forming islands. 



CLASS HYDROZOA (hi dro zo'a). 



The common Hydra of every fresh-water pool and 

 slowly running stream, introduces us to the HYDROZOA. 



ORDER HYDROIDEA (hi droicl'e a). 



The Hydra is about one fourth of an inch in length, and 

 is often of a deep green, or brown color. By reference to 



A, The ceiis with 



its " lasso " partly shot forth. 

 7?, The same completely ex- 

 tended. 



