CRUSTACEA OF ALABAMA. 45 



United States Fish Commission as G. pugnax, reveals no differences. The southern 

 specimens seem to attain a greater size. 



The essential points in the description are the following : Carapace smooth, mer- 

 opodite of larger male cheliped with tuberculate margins, carpopodite with an oblique 

 tuberculate ridge passing from the lower margin of the thumb on the inside upward and 

 backward, inner and outer surfaces pustulate, finger longer than the thumb, strongly 

 curved apically, thumb straight, lower outline of entire hand nearly straight. 



ORDER MACROURA. 

 (Shrimp-like Crustacea.) 



FAMILY PAL/EMONIDyE. 

 (Shrimps and Prawns.) 



This family is quite abundantly represented in the fresh and salt waters of the state. 

 Unfortunately they have not been even superficially studied, the following forms being 

 such only as have come under the observation of the writer. 



From the crayfish the members of this family may be recognized by the compressed 

 abdomen, which has no transverse channel and has free lower margins. There are but 

 two pairs of chelate feet. 



GENUS PAL^MON. 



Carapace extended into a long, serrate, plate-like rostrum ; antennules with two 

 multi-articulate flagella, the inner being appendaged ; mandible with three-jointed palp. 



Palaemon ohionis, Smith. 



It is possible that this species may be found in northern Alabama. 



GENUS PAL^EMONETES. 



This genus differs from Paleemon most notably in the absence of the mandiblar palp. 

 It is represented by at least two species in Alabama, one being as abundant in salt as 

 the other in fresh water. 



Palaemonetes vulgaris, stimpson. 



(Plate IV, Fig. 1.) 

 The common prawn is abundant among the eel grass of Mississippi sound and other 



