192 bulletin: museum of comparative zoology. 



lateral slits long and deep ; proboscis pore terminal ; mouth large,, 

 and situated behind the ganglia; esophageal region mostly rounded; 

 intestinal region broad and flat with thin lateral margins ; the pos- 

 terior end extremely flattened and provided with a delicate caudal 

 cirrus, which extends ventrally beyond the opening of the intestine, 

 and in most species is easily broken off. Eyes often wanting. 

 Body commonly of a nearly homogeneous color, without distinct 

 markings (such as longitudinal and circular bands and rings). 



Proboscis sheath readies to posterior end of body ; proboscis 

 very long and strong. Intestinal pouches deep and mostly forked 

 peripherally ; central intestinal canal comparatively narrow. Neu- 

 rochord cells probably commonly present in brain and lateral nerve 

 cords, though they have as yet been found in but few species. 



Ten species of this cosmopolitan genus are described on the fol- 

 lowing pages as occurring in the region covered by this report. But 

 a single one of these (C. marr/inatus) has been found in other 

 parts of the w^orld. Four species are described as new. 



31. Cerebratulus herculeus Coe. 



Proc. Wash. Acad. Sci., 3, p. 75, PI. 1, fig. 5, 1901 ; Harriman 

 Alaska Expedition, 11, p. 75, 1904. 



PI. 3, fig. 32. 



Representatives of this species attain gigantic proportions and are 

 among the largest nemerteans known. Fully mature individuals 

 are often more than 2 meters in length and more than 25 mm. in 

 width. The body is comparatively short and thick, except when 

 fully extended ; the head is very short, thick and bluntly pointed, 

 cephalic furrows short (PI. 3, fig. 32), mouth large. Esophageal 

 region very short, rounded ; caudal cirrus comparatively small ; pro- 

 boscis large, colorless ; ocelli wanting. 



Color dark brown or reddish brown (PI. 3, fig. 32), somewhat 

 less bright on ventral surface. 



In spite of their great size, the worms are not clumsy, but swim 

 gracefully and rapidly and move actively through their burrows. 



Habitat. — - Sitka, Alaska (Coe, : 01, p. 75), in soft mud, associated 

 with 0. marginatus ; southern Alaska (Griffin, C. sp.?, '98, p. 



