NO. 13 COE : REVISION OF THE NEMERTEAN FAUNA 263 



3. Caudal cirrus absent; proboscis sheath usually much shorter 



than body 4 



3. Caudal cirrus present; proboscis sheath usually nearly as long 



as body 5 



4. Body remarkably thick and massive, usually nearly cylindrical 

 when fully extended but broad and much flattened in intestinal 

 region when partially contracted; ocelli absent; muscular layers 



of body wall with reddish tinge Euborlasia 



4. Body long and slender, filiform in some species, rounded or flat- 

 tened in others, very contractile; ocelli present in most species 

 Lineus 



5. Body rather soft, usually flattened ; lateral margins not thin ; not 

 adapted for swimming; mouth small and round; proboscis 

 sheath often much shorter than body, but proboscis very slender 

 and much longer than body ; ocelli usually present . . . Micrura 



5. Body firm, long and ribbonlike; much flattened in intestinal re- 

 gion, with very thin lateral margins and well adapted for swim- 

 ming; body less contractile than in other genera; dorsoventral 

 and diagonal muscles well developed ; mouth large and elon- 

 gated in some species ; ocelli very small or absent in most species 

 Cerebratulus 



Genus ZYGEUPOLIA Thompson 

 Only a single species of this genus is known at present. 



17. Zygeupolia rubens (Coe), 1895 



Valencinia rubens Coe, 1895; Zygeupolia littoralis Thompson, 1900, 

 1902; Coe, 1905. 



Habitat. Common between tidemarks on sandy shores of harbors and 

 bays. 



Distribution. Southern New England and on the Pacific coast from 

 Monterey Bay, California, to Ensenada, Mexico. 



Genus EUBORLASIA Vaillant 

 Three species of this genus have been found on the Pacific coast. 



Key to Species 



1. Body encircled by conspicuously colored rings usually darker 



than adjacent surface nigrocincta 



1. Body without conspicuously colored rings 2 



