118 THE HISTORY OF ANIMALS. [B. V. 



10. AmoDg those that are not locomotive, the pinnae are 

 fixed ; the solens and conchas remain on one spot, though 

 not fixed, and do not survive separation from their home. 

 The nature of the aster 1 is so hot, that if it is captured 

 immediately after swallowing anything, its food is found 

 digested ; and they say that it is very troublesome in the 

 PyrrhaBan Euripus. Its form is like the paintings of a 

 star. The creatures called pneumones are spontaneously 

 produced. The shell which painters use is very thick, and 

 the pigment is produced on the outside of the shell ; they 

 are principally found in the neighbourhood of Caria. 



11. The carcinium also originates in earth and mud, and 

 afterwards makes its way into an empty shell, and when it 

 grows too large for that, it leaves it for a larger one, as the 

 shell of the nerita, strombus, and such like ; it frequently 

 occurs in the small ceryx. When it has entered the shell, 

 it carries it about and lives in it, except that as it grows it 

 migrates into a larger shell. 



CHAPTEB XIY. 



1. THE nature of the testacea is the same as that of crea- 

 tures without shells, as the cnidae 2 and sponges, which inha- 

 bit the holes in rocks. There are two kinds of cnidse, some 

 which live in holes in the rocks, and cannot be separated 

 from them, and other migrating species which live upon the 

 smooth flat surface of the rocks. (The patella also is free 

 and locomotive.) In the interior of the sponges are found 

 the creatures called pinnophy laces, and the interior is closed 

 with a net like a spider's web, and small fish are captured 

 by opening and closing this web, for it opens as they ap- 

 proach, and closes upon them when they have entered. 



2. There are three kinds of sponges ; one of them is thin, 

 the other is thick, and the third, which is called the 

 Achillean sponge, is slender, compact, and very strong ; it 

 is placed beneath helmets and thigh-pieces, for the sake of 

 deadening the sound of blows ; this kind is very rare. Among 

 the compact kinds, those which are very hard and rough are 

 called tragi. They all grow upon the rock or near the 

 shore, and obtain their food from the mud. This is evident, 

 for they are full of mud when they are captured. This is 

 1 Star-Ssli. 2 Actinia. 



