176 BULLETIN: MUSEUM OF COMPARATIVE ZOOLOGY. 



middle portions, narrower near esophageal region, and narrowing 

 gradually towards posterior end, which is, however, remarkably 

 thick and rather sharply truncated. Anal opening terminal, con- 

 spicuous, colorless. Intestinal region ringed with numerous deep 

 constrictions. A rather conspicuous, but not shar])ly demarcated, 

 rounded ridge extends in the median dorsal line along the whole 

 length of intestinal region (PI. 4, fig. 40) . 



When contracted, as is the single specimen at hand, the intestinal 

 region is much flattened dorso-ventrally, tlie ventral surface becom- 

 ing strongly concave and the dorsal surface decidedly convex. 



Head comparatively small (PI. 4, fig. 40), short, broad, pointed 

 in front, not marked off from body; proboscis pore terminal. In 

 the single specimen at hand the anterior portion of head, or snout, 

 is sharply marked off from the posterior portion by an annular con- 

 striction, which is probably wanting in life. Cephalic furrows re- 

 markably short and inconspicuous as compared with the great size 

 of the worm, measuring but 3 mm. in length, and extending pos- 

 teriorly but little farther than the annular constriction which occurs 

 in this specimen behind the snout; they are incom})letely separated 

 from the proboscis pore anteriorly. There is also a rather conspicu- 

 ous vertical groove on the tip of the snout after preservation, so that 

 when viewed directly from in front the tip of snout seems to be 

 divided into four sections of equal size by the horizontal and vertical 

 grooves, with the proboscis pore at their intersection. 



Mouth is of large size, extending forward nearly as far as the 

 posterior ends of the cephalic furrows and nearly to the annular con- 

 striction on head. Its length is 9 mm. in this specimen. 



Color. — As preserved in alcohol color of body, except the head, 

 is dark brown with a greenish tinge ; head much paler, with numer- 

 ous brown mottlings both above and below. 



Serial sections of so gigantic a worm would obviously be too 

 cumbersome to study as a series, and I have therefore not investi- 

 gated the details of its internal anatomy. A section through esophag- 

 eal region reveals an extremely massive outer longitudinal muscular 

 layer 2i mm. in thickness, while the circular muscular layer is but 

 \ mm. thick, and the internal longitudinal muscles much thinner. 

 Lateral nerve cords are each more than half a millimeter in diameter. 

 In intestinal region muscular layers ai-e all comparatively thin ; the 

 median lumen of intestinal canal in middle portions of body raeas- 



