356 REPORT OF NEW JERSEY STATE MUSEUM. 



large spine of inner edge. Merus smooth, upper edge with two, 

 rarely more or many as four strong spines short space from dis- 

 tal end, lower edge with two rows of strong spines, inner row of 

 four to ten, largest distally, and outer row of two to three spines. 

 Also spine at outer articulation of merus with carpus. Ischium 

 of third peraeopods hooked in male, of first form strong and sub^- 

 conic. Coxa of hind peraeopods without crests or tubercles in 

 male. 



First pleopods in male of first form rather strong, short, 

 not extending beyond front edge of coxopodites of third peraeo- 

 pods, not articulated basally, straight, and two parts separated 

 at tips only short distance. Tips crossed or twisted, divergent, 

 that of gradually tapering inner part soft directed obliquely out, 

 and horny gradually tapering outer part directed obliquely for- 

 ward and slightly inward. Annulus ventralis in female trans- 

 versely rhombiform, with short transverse groove slightly behind 

 middle and sigmoid longitudinal fissure. Anterior to central 

 groove on each side of fissure strong tuberculiform elevation so 

 that fissure placed in rather deep depression. Posterior to central 

 groove, slight elevation over which fissure passes. 



Color greenish on upper surface, mottled with darker green, 

 especially on chelae. Finger tips orange, preceded by dark green 

 ring, which extends along outer border of hand to wrists. Ab- 

 dominal somites ornate with interrupted transverse chestnut- 

 colored double bands and under surface of lighter hue. Length 

 I20 mm. 



Remarks. — This is our common river species, living in the 

 ponds and canals of our lowlands. It is characteristic of the 

 Atlantic Coastal Plain and Piedmont region, in the States of 

 New Jersey, Pennsylvania, Maryland, District of Columbia and 

 Virginia , doubtless also Delaware. In the Delaware it does not 

 seem to go much above Trenton, according to Ortmann rarely 

 to New Hope, and is more abundant in the tidal region. Tike 

 some other lowland aquatic animals it is likely an ancient type, 

 and according to Ortmann is a "Tertiary relic at the northern 

 extremity of the coastal plain, which has not been able to expand 

 its area to any considerable degree in Postglacial times." 



