CANCROIDEA. 



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f. 2), but according to Edwards (Crust., i. 461), that species, besides 

 having the fourth lateral tooth rudimentary, has the third tooth but 

 little salient ; while in our species the latter is quite as prominent as 

 the second, and these two are the largest ; also, the external frontal 

 teeth are pointed and small, while they are rounded or subtruncate 

 in the crassimana. It is also near the Tlialamita cwruleipes of Hom- 

 bron and Jacquinot (Crust., Voy. au Pole Sud, PL 5, f. 6), but that 

 has the fourth lateral tooth much larger than in the above, although 

 still a little shorter than the rest, and the peduncle of the eye is set 

 around with short spines or processes, while in the above, there are 

 no projecting points ; the hand also is much less stout. The small 

 tubercles of the hand are scattered over the upper and lateral surface, 

 as far down as the first costa. The under and lower half of inner 

 surface of the hand is smooth. The posterior natatory legs are smaller 

 than usual in this genus. 



Genus CHAKYBDIS. 



Carapax angustior. Frons dimidio latitudinis brevior, et margo antero- 

 lateral is obliquus. Ariiculus antennae externce lmus minus oblongus, 

 articulo sequente a hiatu orbitce paulum remote. 



Carapax narrower than in Tlialamita. Front shorter than half the 

 breadth of carapax, and antero-lateral margin oblique. First joint 

 of outer antennse less oblong, and the following joint much less dis- 

 tant from the orbit. 



Charybdis orientalis. 



Carapax lo3vis, regione mediand 2—3-lineis elevatis inter sectd, fronte 

 arcuato, dentibus valde obtusis, Stio triangulato, margine antero-late- 

 rali Q-dentato, dentibus acutis, 2do minimo, postremo non longiore. 



Carapax smooth, median region crossed by two or three raised lines, 

 front arcuate, teeth very obtuse, third triangular, antero-lateral 

 margin six-toothed, teeth acute, second very small, last not longer 

 than others. 



Plate 17, fig. 10, carapax, natural size. 



72 



