OF ARTS AND SCIENCES. 135 



Hand smooth, cylindrical, inflated ; fingers slender, incurved at the 

 tips. Carpus smooth, armed with a single spine on the antero-iuferior 

 border. Meros provided with a single spine near the distal end of the 

 superior margin and two or three below. Third segment of second 

 and third pairs of legs hooked. First pair of abdominal appendages 

 straight, bifid, inner part ending in a straight, acute tip, outer part 

 split at the tip into two straight acute points. 



In the second form of the male the hooks upon the thoracic legs 

 are very slightly developed, and the first abdominal appendages are less 

 deeply cleft, with blunter and less finished tips. The chela is shorter. 



In the female the chela is much shorter, broader, and less cylindrical, 

 the abdomen broader. Annulus ventralis a transverse curved ridge, 

 the hind side of the ridge concave. 



Length, 19 to 27 mm. 



Locality. Near New Orleans, La. 



Found with G. Clarkii in the collection made by Dr. R. W. Shu- 

 feldt, U. S. A., in 1883, now in the U. S. National Museum. 



This is a minute species closely related to C. 3Iontezumce from 

 Mexico. Like that species, it has the second and third pairs of legs 

 hooked in the male, a condition which normally obtains in no other 

 species known.* C. Slntfeldtii is distinguished from G. Montezumce by 

 the presence of a lateral spine on the carapace and by the form of the 

 male appendages. In the latter species the tips of these appendages 

 are recurved, the inner part flattened at the end into a spoon-shaped 

 surface. In G. Shufeldtii the tips of these organs are straight, and 

 each of the three points in which they terminate is acute. 



LIST OF THE KNOWN. SPECIES OF CAMBARUS AND ASTACUS. 



1. Cambarus Blandingii. 



Astacus Blandingii, Harlan, Trans. Amer. Philosoph, Soc, 

 in. 464. 1830. — Med. and Phys. Res., p. 229, fig. 1. 1835. 



Astacus ( Gambarus) Blandingii, Erichson, Arch. Naturgesch., 

 Jahrg. XIL, Bd. L, 98. 1846. 



? Astacus Blandingii, Le Conte, Proc. Acad. Nat. Sci. Phila., 

 VIL 400. 1855. 



* I have seen two or three abnormal specimens of C. virilis and C. propinquus 

 with a like disposition of hooks on the legs. 



