ISOPODS OF NORTH AMERICA. 



185 



and both are pointed at the posterior extremity. The inner branch is 

 very slightly excavate on the exterior margin about 1 mm. from the 

 extremity. Both branches are denticulate and furnished with spines. 

 The first three pairs of legs are prehensile, the last four pairs 

 ambulatory. All the legs are very slender and free from spines. 



JEGA SYMMETRICA Richardson. 

 JEga symmetrica RICHARDSON, Bull. U. S. Fish Comm., XXIV, 1905, pp. 211-212. 



Localities. Vicinity of Naha Bay, Behm Ganal, southeast Alaska; 

 Queen Charlotte Sound, off Fort Rupert, Vancouver 

 Island, British Columbia. 



Body ovate, twice as long as broad. Color yellow, 

 densety covered with light-brown dots, which form 

 a regular line along the margin of each segment. 

 Surface smooth. Head with frontal margin pro- 

 duced in a median point, which arches over the basal 

 joints of the antennae and meets the frontal lamina 

 or interantennal plate on the underside. The eyes 

 are narrow and elongate, composed of numerous 

 ocelli. They are separated in front by a distance 

 equal to the length of one eye. The first pair of 

 antennae extend to the posterior margin of the first 

 thoracic segment; the joints of the peduncle are not 

 dilated, although the first two joints are somewhat 

 wider than the third, nor is there a process at the distal extremity 



of the second joint. The first two joints 

 are of equal length; the third is as long 

 as the first two together; the flagellum is 

 composed of eleven joints. The second 

 pair of antennae reach the middle of the 

 third thoracic segment; the flagellum is 

 composed of sixteen joints. The frontal 

 lamina or interantennal plate is conical, 

 with the distal end flat, the proximal end 

 produced to an acute point. 



The several segments of the thorax are 

 about equal in length, the last one being 

 slightly shorter. The epimera are large, 

 subquadrate, with the outer distal angle 

 of the last three produced posteriorly beyond the margin of their 

 respective segments. 



The first three pairs of legs have the propodus beset with three 

 small spines along the inrter margin; the carpus is short and armed 

 with one spine; the merus is provided with five spines and the ischium 



FIG. 169. ^EGA SYM- 

 METRICA. x 



FIG. 170. YGA SYMMETRICA. o, MAXIL- 

 LIPED. x 27J. 6, PALP OF SAME, x 51|. 



