DECAPODJ. PENs'EAD.l':. 



MACROURA. 



GENUS PASIPH^A. Sav. 



Alpheus. Risso. 



Pasiph^ea. Savigny, Risso, Desmar. Latr. Leach, Edw. 



Generic character. — External antennm placed beneath the in- 

 ternal ; the basal joint of the peduncle narrower than the succeed- 

 ing one. Internal antennce with the peduncle slender, and ter- 

 minated by two filaments, one of which is considerably longer than 

 the other. External pedipalps very long, slender, and pediform ; 

 furnished at the base with a lamellar ciliated palp. First and se- 

 cond pairs of legs didactyle, rather robust, nearly of equiil length ; 

 the fingers slender and curved ; third, fourth, and fifth pairs very 

 slender, monodactyle, the fourth pair the shortest. Carapace very 

 much elongated, compressed, narrowed anteriorly. Ahdomen very 

 long, much compressed ; the fifth segment broad and squared at 

 the lateral margin ; the sixth very long ; the seventh narrow and 

 wedge-shaped ; the false feet of the first segment with the filaments 

 rudimentary, the others with two equal. 



The history of this remtirkable genus has hitherto been 

 involved in some obscurity. In the description of our 

 species I have given some reasons for beheving that as yet 

 one species only is known. 



