ORDER ACTINOIDEA. 35 



vals, and thus a degree of uniformity obtains between the young and 

 adult individuals, which is indicated in their coralla. 



26. The process of digestion appears to be extremely simple. The 

 food is retained for a while in the stomach, and there acted upon by 

 the gastric juice supplied from its walls, after which the refuse matter 

 is ejected by the mouth. The farther change to chyle probably takes 

 place below in the visceral cavity, where a part of the nutrient fluid 

 is absorbed, while another portion is distributed for assimilation 

 throughout the various cavities, lacunes, or pores in the tissues of the 

 animal. Thus the processes of aeration and assimilation go on toge- 

 ther throughout the whole structure of the Actinia, and there is a 

 water-and-chyle circulation, nearly in the same manner as we have 

 described with regard to the Hydroidea. No proper circulating fluid 

 independent of this, and no branchiae, have been observed in these 

 animals. Whether there are any excrementary secretions attending 

 this assimilating process, as in other animals, has not been directly 

 proved. Yet it is probable that the tissues about the visceral cavity, 

 among their many functions, include the means of performing this 

 part in the economy of the animal; and the waters expelled, in 

 different ways, by the polyp, may carry off such secretions. It is 

 remarkable, that while the biliary glands are of unusual size in the 

 lower animals generally, in the Actiniae they are wanting; and this 

 is no doubt connected with the fact that these animals are bathed so 

 freely inside and out by the sea-water, which renders special organs 

 unnecessary. If the above supposition be true, it is not proper to 

 consider the mouth of a polyp as alone the only passage for the ex- 

 crements. It ejects the refuse indigestible matters from the stomach, 

 but only in part the proper excrements of the animal. 



The Actinia; receive almost any animal food that falls in their way. 

 Crabs, molluscs, the smaller fish, and other marine animals, are their 

 common prey. They have been seen with a large bivalve in their 

 stomachs, from which the animal had been removed by their powerful 

 gastric solvents. 



27. The function of reproduction belongs to the visceral lamellse 

 (\ 25), part of which are spermatic and part ovarian. 



The spermatic lamellse are distinguished by being margined by 

 a white capillary cord. This cord is much convoluted, and is at- 

 tached to the lamellse by a thin and extensile membrane, which has 

 a mesenterydike appearance.* The quantity of these cords in an 



' Similar to figures 3 6, 3 c, 3J~, plate 30. 



