COEALLINES. 



129 



Fig. 48. Three Polyps of the Coral. 

 (Lacaze-Duthiers.) 



eight folds, radiating round a central pore, which presents a star-like 

 appearance. This pore as it opens gives to the polyps the op- 

 portunity of coming out. Its 

 edge presents a reddish calyx, 

 like the rest of the hark, the 

 festooned throat of which pre- 

 sents eight dentations. 



The polyp itself (Fig. 48) is 

 formed of a whitish membra- 

 nous tube, nearly cylindrical, 

 having an upper disk, surrounded 

 by its eight tentacula, bearing 

 many delicate fibres spreading 

 out laterally. This assemblage 

 of tentacula resembles the corolla 

 of some flowers ; its form is very 

 variable, but always truly elegant. 

 Fig. 49 (which is borrowed 

 from M. Lacaze-Duthiers' great 

 work) represents one of these forms of the coral. 



The arms of the polyps are at times subject to violent agitation : the 

 tentacula become much excited. 

 If this excitement continues, the 

 tentacula can be seen to fold and 

 roll themselves up, as shown in 

 Fig. 50. If we look at the ex- 

 panded disk, we see that the 

 eight tentacula attach themselves 

 to the body, describing a space 

 perfectly circular, in the middle 

 of which rises a small mammal, 

 the summit of which is occupied 

 by a small slit like two rounded 

 lips. This is the mouth of the 

 polyps, the form being very va- 

 riable, but well represented in 

 Fig. 50, where the organ under 

 consideration is displayed. 



