VOL. XI, pp. 109-110 MAY 13, 1897 



PROCEEDINGS 



OF THK 



BIOLOGICAL SOCIETY OF WASHINGTON 



SYNOPSIS OF THE AMERICAN SPECIES OF ETHUSA, 

 WITH DESCRIPTION OF A NEW SPECIES.* 



BY MARY J. RATHBUN. 



The type species of Ethusa, E. mascarone (Herbst) of the 

 Mediterranean, is represented in the West Indian region by a 

 form so slightly different that it cannot be regarded as more 

 than a subspecies. E. mascarone americana. E. microphthalma is 

 found in the deeper waters off the Atlantic coast of North 

 America; E. lata and E. ciliatifrons occur on the Pacific coast 

 of tropical America. To these a fifth species is now added, 

 E. tenuipes, from the Gulf of Mexico and Florida Keys. 



SYNOPSIS OF AMERICAN SPECIES OP Ethusa. 



A. Eye-stalks long, extending laterally beyond the postorbital spine. 



mascarone americana A. Milne Edwards. 

 A'. Eye- stalks short, directed forward. 



B. Branchio-cardiac lines meeting in front of the heart. 



ciliatifrons Faxon. 



W. Branchio-cardiac lines not meeting in front of the heart. 

 C. Dactyli of second and third pairs of legs broad, vertically com 

 pressed. 



D. Third joint of antennae reaching the extremity of the frontal 



teeth. lata Rathbun = pubescens Faxon. 



D/ Third joint of antennae not reaching the extremity of the 



frontal teeth. microphthalma Smith. 



C 7 . Dactyli of second and third pairs of legs slender, not vertically 



compressed. tenuipes Rathbun, new species. 



* Published with the permission of the Secretary of the Smithsonian 

 Institution. 



25 BIOL. Soc. WASH., VOL. XI, 1897 (109) 



