232 



SUBKINGDOM AKTICULATA. 



ORDER TETRADECAPODA. 



General Characteristics.— The Tetradecapods (fowr- 



teen-footed) have sessile 

 (low-sitting) eyes and 

 all the segments of the 

 thorax free. 



The Amphipods 

 have the four anterior 

 pairs of feet directed 

 forward and the three 

 posterior backward. 

 They live in both salt 

 and fresh water, and 

 are abundant on the 

 sea-shore between tide- 

 marks. (Fig. 395.) 



Fig. 396. 



a. Taritnis locusia : 

 b. OrchesCia longiconiis, Sand-fleas. 



The Isopods have a flattened body, 

 the three anterior pairs of feet directed --^Sf,'' 

 forward and the four posterior pairs .'/ 

 backward. The gills are borne under / 

 the abdomen. Soiv-bugs are familiar 

 examples. 



ORDER PHTLLOPODA. 



General Characteristics. — The 

 Phyllopods liave from 10 to 60 pairs 

 of leaf-like feet, answering the purpose 

 of gills. They are found in both salt 

 and fresh water. Fig. 396 represents 

 a species discovered by Dr. E. Coues, 

 in small prairie pools in Montana. 



Hermit Crab i8 protected only in itont, and so "backs" into tlie spiral shells of 

 other MoUusks, leaving its temporary home only when outgrown. The Marine 

 Lobster has a broad fln at the base of its tail, by one stroke of whicli it can spring 

 backward twenty feet. 



