79 



sea-blubber, for example, there is, on the lower 

 surface of the body, a simple aperture or mouth, 

 leading by four passages into the same number 

 of sacs or stomachs, which are not so much 

 formed by a distinct membrane, as scooped out 

 of the gelatinous substance of the body ; they 

 are, nevertheless, capable of digesting the small 

 prickly fishes on which these animals subsist, as 

 well as other substances apparently easily capable 

 of resisting their action. But a more perfect 

 modification of digestive apparatus is most com- 

 mon, not only in the higher classes of animals, 

 but even in worms and insects. Thus, among 

 the Crustacea, the sea-urchin has the gullet, sto- 

 mach and intestinal canal quite distinct from 

 each other ; and this is still more obvious in 

 some of the Testacea, as in one kind of snail, in 

 which there is found besides a very large liver, 

 a proper membrane, enclosing all these parts, as 

 in the higher classes of animals, and called peri- 

 toneum. The same is the case, among the mol- 

 luscous animals, in the cuttle, in which the gullet 

 expands into a kind of craw or crop, similar to 

 what is met with in some birds, and the stomach 

 also is firm and fleshy like a gizzard. A similar 

 crop and gizzard also are met with in some other 

 animals of this tribe, as in the earth worm, in 

 which the latter is often found to contain little 

 pieces of earthy matter, which the animal seems 

 to swallow as some kinds of birds are known 

 to do for the purpose of assisting the attrition 

 of the food. In so far they perform the office of 



M 



