ALASKA NEMERTEANS 75 



27. CEREBRATULUS HERCULEUS sp. nov. 



pi. i, fig. 5. 



Body very large, stout, thick, broad, attaining a length of 2 meters 

 or more, and a breadth of more than 25 mm. ; remarkably broad when 

 contracted, the body somewhat resembling that of a leech. One speci- 

 men, preserved in alcohol and strongly contracted, now measures 300 

 mm. in length, 25 mm. in width in intestinal region; 18 mm. in width 

 and 15 mm. in thickness in esophagal region. The length of the 

 esophagal region in this specimen is only about 55 mm. after preser- 

 vation. 



Head very short, thick, and bluntly pointed. Cephalic slits short, 

 separated in front, reaching back in the alcoholic specimen but 7 mm. 

 Mouth large, situated as far back as the posterior end of the cephalic 

 furrows. 



Esophagal region short and thick ; intestinal region very broad and 

 flat, with thin, wavy margins in life. Posterior extremity provided 

 with a pale caudal cirrus of comparatively small size. Proboscis 

 large, colorless, fully equal in size to that of a large specimen of C. 

 marginatus. No ocelli. 



Color. Color very dark brown or reddish brown throughout the 

 whole dorsal surface, rather paler and less bright ventrally. 



This gigantic Nemertean is not clumsy in its movements, but is 

 active, and swims rapidly and gracefully. It was met with only at 

 Sitka, where it occurred in considerable numbers in mud at low water 

 mark, associated with C. marginatus. The worms are fragile, and 

 break spontaneously unless carefully handled. 



28. CEREBRATULUS MARGINATUS Renier. 



Cerebratulus marginatus RENIER, Prospetto della Classe dei Vermi (t. Burger), 



1804, 

 C. angulatus MclNTOSH, British Annelids ; Pt. I, Nemerteans, p. 195, Ray 



Society, 1872-73. 

 C. fuscus VERRILL, Trans. Connecticut Acad. , vui, p. 438, 1892. 



This large and active Nemertean was found in several localities 

 about Sitka, but not in great numbers. The individuals there found 

 possess the typical color of the species, with which they agree exter- 

 nally in every detail except the shape of the body. All the Alaska 

 specimens are much shorter and comparatively broader than those I 

 have seen in Naples, although careful study of microscopic sections 

 revealed no essential anatomical differences. It is therefore probable 

 that this is but a local peculiarity of a single widely distributed species. 



