248 CRUSTACEA OF THE UNITED STATES. [May. 



Genus PAL^MON. 

 Exterior antenna inserted below the line of the inte- 

 rior ones, and furnished with a large scale at base; inte- 

 rior antenna with three setae; exterior ^amella of the tail 

 undivided; ultimate joint of the external palpi shorter 

 than the preceding; yowr anterior feet didactyle^ first pair 

 smaller. 



SPECIES. 



1. P. * vulgaris. Rostrum acute, with eight or nine 

 teeth above, and three or four beneath; fingers of the lar- 

 ger pair of feet shorter than the palm of the hand. 



Inhabits bays and estuaries. Very common. 



Bostrum as long as the scales of the antennae, ciliated 

 between the teeth; thorax armed with two spines on each 

 side, which are equal, and placed one at the base of the 

 interior antennae, and the other at the base of the exterior 

 ones; an impressed line passes between these spines, and 

 terminates about the middle of the side, an obsolete, ob- 

 lique, abbreviated one originates at the superior margin 

 of the orbit of the eye; peduncle of the scale armed with 

 a spine at the exterior tip; first joint of the peduncle of 

 the interior antennae concave above, and furnished with a 

 spine near the external base, and another near the exter- 

 nal tip; carpus of the first pair of feet rather longer than 

 the preceding joint, armed with a spine on the inner tip, 

 hand elongate oval, unarmed, about one half as long as 

 the carpus, fingers equal; carpus of the second pair, near- 

 ly equal to the preceding joint, unarmed, shorter than the 

 palm of the hand, hand elongated, fingers uncinate at tip, 

 shorter than the hand, linear, equal, with two or three 

 small, obtuse teeth at the base, middle process of the ap- 



