210 SUPPLEMENT 



are terminated by small claws. They are in general larger, 

 and more especially thicker than the feet properly so called ; 

 nevertheless, the latter are sometimes much the largest. In a 

 great number of genera they are equal in size one to the 

 other, but in some one is always thicker. Sometimes they are 

 very long and slender ; sometimes very short, and almost con- 

 cealed. They also present considerable varieties of surface. 



The proper feet vary only in length, position, and the form 

 of the tarsus : in general they decrease in size regularly from 

 the first pair, but in some genera the second and third are the 

 largest. In the crabs which swim well they are all larger than 

 in those which frequent the land, and in a direction more hori- 

 zontal. The land-crabs, and those which frequent shores, all 

 have the last articulation of their feet more robust, but little 

 arched, and conical. In those which swim more than they 

 walk, this articulation is very much depressed, ovo'id, and 

 ciliated on its edges. In the macrouri the feet are very simi- 

 lar to those of the brachyuri, but in general more elongated. 

 Some macrouri have no claws or forceps. Besides the true 

 feet, these Crustacea have five pair of what are called false feet 

 under the tail, terminated either by two plates or two threads. 



The SquillaB have received the denomination of Stomapods, 

 from the disposition of the feet, or rather of the appendages 

 so regarded, which surround the mouth. We have already 

 seen, in describing the parts of the mouth, how emTjarrassing 

 it is to give a suitable designation to those appendages, which 

 many naturalists consider as feet, while others regard them as 

 dependencies of the mouth. Be this, however, as it may, 

 they present the same number of articulations as the ordinary 

 feet of the decapods. The modifications of the feet in the 

 other divisions are very various, but these modifications need 

 not be described here. The caligi, however, we may observe," 

 have very short feet, arched in the form of hooks, and serving, 

 like those of Cymathoe, to fasten on the fleshy parts of those 



