MARINE ANIMALS. 



91 



transversely to the prismatic apertures; the tubes thus formed are bent aside 

 to admit the aperture, and again pursue their course. 



There is a very beautiful species of shell found in the Australian seas, 

 sometimes at a considerable depth, known as a Terehratula. This creature 

 is furnished with two arms, which arc coiled up within the shell, which is a 

 bivalve, as represented in Fig. 1, and can be extended at pleasure to reach 



Fio. 1.— Spirifer Kostratus. 



Fio. 2.— Can-iuge Sprmg, shewing a similar apparatus. 



its food; the apparatus by which it is attached to the shell is known as the 

 coach or carriage spring, (See Fig. 2.) and hence the shell has that name given 

 to it. In these shells there is a living mantle, and they 

 therefore come under the class Palliohranchiata ; and in 

 some the cellular formation is found to vary in size; and 

 in some of these, Mr. John Quekett, the celebrated 

 microscopist, has discovered Cilia, which he supposes 

 to be used by the animal for the purpose of transmitting 

 LaminEe ' of"^ Terebratuia Water from the tubcs. (See Fig. 3.) In one genus, 

 cc. ' '' ^^'"^ ^ ' ^ Lingula, (See Fig. 4.) which is of an intensely green 



