196 REPORT OF NEW JERSEY STATE MUSEUM. 



in this species, many often being pale or dark, in striking con- 

 trast with others. 



Possibly Gaiuiiiariis niiniis Say is identical with this species^ 

 though S. I. Smith says that it is very likely not a true Ganir- 

 uiarus. Say's account is as follows : Body whitish , with a 

 few pale fulvous lateral spots. Eyes reniform, blackish, placed 

 at the exterior base of the superior antennae. Superior an- 

 tennae obviously longer than inferior ones. Seta [secondary 

 flagellum] short, attaining the tip of the second articulation 

 of the terminal joint [flagellum]. Terminal joint with about 

 twelve articulations. Length three-twentieths of an inch 

 [nearly 4 mm.]. Found in brooks under stones, and may be 

 readily discovered by taking a stone out of the water, and 

 inspecting its inferior surface. 



Genus ELASMOPUS A. Costa. 



Elasmopus A. Costa, Rend, della Soc. Reale Borbonica, II, 1853, p. 170 (175). 

 Type Elasmopus rapax A. Costa, monotypic. 



Body comparatively strongly built and quite smooth, with 

 coxal plates of moderate size, fourth pair largest and distinctly 

 emarginated posteriorly. Cephalon without any rostrum, with 

 lateral corners rounded off. Eyes well developed. Superior 

 antennas longer than inferior, and provided with comparatively 

 small accessory appendage. Oral parts normal. Gnathopoda 

 subcheliform, rather unecjual, posterior ones much larger and 

 very strongly developed in male. Posterior pairs of perseopoda 

 unusually robust, but joints more or less expanded, and basal 

 one very large and laminar. Last pair of uropoda not very 

 elongated, and somewhat robust in structure, with comparatively 

 broad rami. Telson laminar, divided by deep narrow cleft intO' 

 two halves, each spinous at tip. 



Species rather few. This genus is largely characterized by its 

 short robust body, powerful development of the posterior 

 gnathopoda, unusually strongly built posterior pairs of perseo- 

 poda, and structure of last pair of uropoda and that of telson. 



