DECAPOD A. ALPHMADJE. 



MACROURA. 



GENUS ALPHEUS. Fabr. 



AsTACCJS, Fabr. 



Pal.^mon, Oliv. 



Cryptothalmus, RafRn. 



ASPHALIUS, Roux. 



Alpheus, Fabr., Latr., Leach, Edw. 



Generic Character. — External antenncE placed beneath, and to 

 the outer side of the inner ; the lamellar palp of moderate size, some- 

 times slender and pointed. Internal antenna; terminating in two 

 filaments, of which the superior is rather thicker than the inferior ; 

 the basal articulation short, and furnished with a spiniform scale. 

 External ])edipalps more or less slender and elongated; terminal 

 joint broad, and somewhat foliaceous. Fi7'st pair of legs didac- 

 tyle, robust, one much larger than the other, and very differently 

 formed : second jxcir also didactyle, very slender ; the carpus multi- 

 articulate : the remaining pairs slender, monodactyle. Carapace 

 extending forwards so as to form an arched covering to the eyes. 

 Rostrum small or wanting. Abdomen long, and much developed. 



Of this genus, which is chiefly confined to hot cHmates, 

 one species only has been found in Britain, and is now 

 first described. 



