NATATORIA. 133 



Phryxus (Kathke). Male, — back convex; belly 

 flat ; feet formed for walking ; gills rudimentary ; 

 antenna? short, slender. Female, — back flat; 

 belly convex ; feet bent up towards the back ; 

 gills large, two-lobed. Parasitic beneath the cara- 

 pace of Hippolyte. 



P. hippolytes. Fig. 228 male ; 229 female; n. s. 



Family II. Ionid^e. 



lone (Latr.). Body very flat, long-oval; false 

 feet shrub-like. Male much smaller than female, 

 and carried beneath her body. Parasitic beneath 

 the carapace of Callianassa. 



I. thoracicus. Fig. 227 ; n. s. 



Tribe II. Natatoria. 



Thorax of seven distinct segments ; 

 seven pairs of feet nearly equally de- 

 veloped ; abdomen very short : 



First five segments of abdomen dis- 

 tinct and moveable. Last false feet 

 with two moveable plates. Head small. 

 Feet in general anchor-like .... Cymothoada. 



First five segments of abdomen sol- 

 dered together. Last false feet with 

 one or two plates, of which only the 

 outer one is moveable. Head large 

 and transverse. All the feet simple 

 and formed for walking Sjphceromadce. 



Thorax of five segments ; first two 

 pairs of feet rudimentary or wanting. 

 Abdomen greatly developed . . . Pranizada. 



