DECAPODA. ALPHEADJE. 



MACROURA. 



GENUS ATHANAS. Leach. 



Generic Character. — External ayitennce not longer than the 

 body; the scale oval ; unidentate on the outer side at the apex. 

 Internal antennce with three filaments, one shorter and thicker 

 than the others. External pedijmlps short and slender. First 

 pair of feet the largest, unequal, didactyle : second pair very 

 small, filiform; the v^rist long and multi-articulate; the hand 

 minutely didactyle : the remaining pairs simple. Carapace ter- 

 minating in a simple rostrum. Abdomen even ; the external plates 

 of the tail transversly divided. 



Of this genus one species only is known. It possesses 

 the peculiarity which is found most strongly marked in the 

 Astacidse, the transverse division of the external lamina of 

 the tail ; a character which also obtains in a less marked 

 degree in Nika^ and some other genera of the Alphead^. 

 It differs from all others of the family in having three 

 filaments to the internal antennte, and from the Pal^mo- 

 NiD^ in the simple form of the rostrum and other cha- 

 racters. 



