558 CRUSTACEA. 



upper mallet-shape, obtuse. Feet of second pair a little longer 

 than third, first joint of carpus about twice as long as second. 

 Third pair of feet rather stout, third joint obtuse at lower apex. 



Plate 35, fig. 9 a, cephalothorax, natural size ; b, profile of front, 

 enlarged four diameters ; 6, upper view of front, enlarged ; c, caudal 

 segment and appendages ; d, larger hand outer surface, natural size : 

 e, same, inner surface (from a larger specimen) ; /, smaller hand ; </, 

 second pair, natural size ; h, outer maxillipeds, enlarged. 



Rio Janeiro ? 



Length, two and a half inches. Second joint of inner antenna' 

 nearly twice the length of first ; basal spine or tooth of inner antenna 1 

 shorter than first joint. Larger hand with lower margin entire, a 

 sulcus in outer surface of lower finger extending along hand, inner 

 surface of hand towards upper margin rough with small tubercles, and 

 somewhat hirsute. Smaller hand rather stout. Carpus of second 

 pair has first joint equal to twice the second, or nearly to the second, 

 third, and fourth together; hand rather longer than fifth joint. 



The species is probably from Rio Janeiro. 



GENUS BET^US, Dana. 



Alpheo oculis antennis pedibusgue affinis. Frons non rostratum. 

 Manus anticce plus minusve inverses, digito mobili inferiore vel exte- 

 rwre. 



Like AlpJiem in the eyes, antenna?, and feet. Front without a beak. 

 Anterior hands more or less inverted, the moveable finger being 

 the lower or outer. 



The front has no trace of a tooth in the species observed, but is 

 sometimes deeply notched at middle. In each of our species, the 

 carpus of the second pair of feet has the first joint two or three times 

 as long as the second joint, and the second, third, and fourth joints 

 are very short and nearly equal. The hands are moderately large, 

 and either equal or unequal. 



