MASTICATORY ORGANS OF CRABS. 85 



Barnacles attached to any object within reach. 

 These facts show that the asceticism of the crab is 

 not voluntary, and that when opportunity occurs, he 

 is as fond of a good dinner as are animals possessed 

 of a higher degree of organization. 



It will be gratifying if other observers are able to 

 verify the circumstance which I shall allude to here- 

 after, and which would seem to show that the 

 exuviation of Crustacea is expedited by affording 

 specimens an unlimited supply of food. 



"The organs for pursuing, seizing, tearing, and 

 comminuting the food of the Brachyurous Decapods/ 

 says Professor Bell, ' are carried to a high degree of 

 development ; . . . . these appendages consist of six 

 pairs, of which some are actual organs of mastication, 

 as the mandibles or the true jaws, the foot jaws or 

 pedipalps, generally serving to keep the food in con- 

 tact with the former, whilst it is being broken up 

 by them. 



'The buccal orifice in the Brachyura occupies the 

 interior face of the cephalic division of the body, and 

 is bounded anteriorly by a crustaceous lamina of 

 determinate form, which has been termed the upper 

 lip, and posteriorly by another, termed the lower lip. 

 The mandibles occupy the sides of the opening. 

 After these, and external to them, are the first, and 

 then the second pair of true jaws, followed by the 

 three pairs of pedipalps or foot jaws, the last of 

 which, when at rest, close the mouth, and include 



