DECAPODA. 

 BRACHYURA. 



Till A. POLITA. 



365 

 CORYSTID^E 



Thia polita, Leach. 



Cancer residuus? HERBST, t. xlviii. f. 1. 



Thiapolita, LEACH, Zool. Miscell. II. t, ciii. GUERIN, Icon, du regno 



anim. t. iii. f. 3. EDW. Hist, des Crust. II. p. 144. 

 Thia DlamriJIii, Risso, Hist. Nat. de 1'Eur. Mend. v. p. 19. 



THE carapace in Thia polita is perfectly smooth and 

 polished ; the circumference is almost entire, excepting a 

 small notch over each orbit ; its outline is contracted to- 

 wards the posterior portion, and the posterior margin is 

 truncated in the male, and slightly hollowed in the female; 

 it is nearly horizontal from the front to the posterior mar- 

 gin, and much arched from side to side ; the front is pro- 

 minent and evenly arched ; the whole of the margin is 

 ciliated with long hair. The orbits are very small, and 

 the minute eyes are ordinarily concealed within them. 

 The anterior pair of legs are robust, the surface polished ; 

 the hand is rounded, the posterior outer angle obliquely 

 cut away for the articulation of the wrist ; the fingers are 

 slightly deflexed, and armed with a few small tubercles. 

 The remaining legs are shorter than the former, the hinder 

 ones being the shortest ; the joints, particularly the pen- 



