1317.] 



GENUS. MONOLEPIS, 155 



An Account of the Crustacea of the United States, Bif 

 Thomas Say, Read November 4, 1817. 



(Continued.) 



Tlie two following .undescribed animals possess cha- 

 racters so distinct irom any genus hitherto established^ 

 that I have thought proper to connect them und<^r a new 

 genus. By the conformation of their organs of locomo- 

 tion, they will serve to approximate still more closely the 

 orders Brachyura and Macroura^ than has been done by 

 the genus Forcellana» To this genus I have applied the 

 name of Monolepis,! from the Greek words signify- 

 ing one and scale^ in allusion to the conformation of the 

 tail. I shall here lay down its cliaracters, at length, dis- 

 tinguishing them into essential, natural, and artificial, and 

 finally note the affinities of the genus. 



OrJe^r MACROURA. 



jy^fac/ intimately united with the thorax; feet ten; ab- 

 domen beneath furnished wdth five pairs of natatory feet; 

 tail with lateral foliaceous lamellss* 



Genus MONOLEPIS.* 



Essential Character, 

 Hind-feet very small, folded on the posterior angle oS 

 the thorax; caudal lamella simple on each side. 

 Artificial Character. 

 Thorax oblong, narrowed before, eq>ual, ernargrnatie 

 over the insertion of the abdomen; eyes very large, remote^ 

 lateral; external pedipalpi incurved, joints subequal, the 



tFrom jttdvos, one, and AeTr;?, a iicale, in allubion to the caudal 

 hunellae,. 



