DESCRIPTIONS OF A NEW GENUS OF ISOPOD CRUSTA- 

 CEANS, AND OF TWO NEW SPECIES FROM SOUTH 

 AMERICA. 



By Harriet Richardson, 



Collaborator, Division oj Marine Invertebrates, United States National Museum. 



Six species heretofore referred to the genus Olrolana are herein 

 transferred to a new genus, of wliich Cirolana orientalis Dana is 

 designated as the type. Two new species of the genus are also 

 described, one collected on the east coast and the other on the west 

 coast of South America. Only one of the six known species is from 

 South America, the others being from North America and the Orient. 



EXCIROL.ANA, new genus. 



Head with the front produced in the middle in a process which 

 separates the basal articles of the antennae and extends anteriorly, 

 becoming dilated at its extremity and confluent with the frontal 

 lamina. 



All the segments of the abdomen with the sides free, those of the 

 fifth not covered by the lateral angles of the preceding segment. 



Uropods and terminal segment of abdomen furnished with long 

 plumose hairs, the outer margin of the external branch being alwa^^s 

 naked. 



Pleopods with both branches long, slender, and tapering. 



Aiouth parts as in the genus Cirolana. 



Type of the genus. — Cirolana orientalis Dana, from the Sulu (Jolo) 

 Sea. 



The other species referred to this genus are : 



Excirolana armata (Dana), from Rio Janeiro, Brazil; 



Excirolana may ana (Ives), from Yucatan; 



Excirolana linguifrons (Richardson) , from Monterey Bay, California ; 



Excirolana cMltoni (Richardson), from San Francisco, 'California; 



Excirolana japonica (Thielemann), from Japan; 

 and the two new species described herein. 



Proceedings U. S. National Museum, Vol, 43-No. 1929. 



201 



