8o COE 



31. CEREBRATULUS MONTGOMERY! sp. nov. 

 pi. vi, figs, i and 2. 



Body large, very long and ribbon-like when fully grown, and much 

 flattened, except in esophagal region. Head variable in shape, ac- 

 cording to state of contraction; sometimes rounded and obtuse, at 

 other times much elongated, pear-shaped, and flattened dorso-ventrally. 

 The anterior portion of the body, back as far as the intestinal region, 

 is narrower and thicker than the posterior portions, and has rounded 

 margins ; in the intestinal region the body is very flat, and the lateral 

 margins are extended to very thin edges. In partial contraction the 

 dorso-ventral muscles, situated a little distance from the outer edge of 

 the margins, contract so strongly as to produce a lateral ridge on each 

 side both above and below the lateral edge. A transverse section con- 

 sequently shows that the lateral margin is thicker distally than it is 

 nearer the median line. These lateral ridges are often seen in speci- 

 mens preserved in alcohol or formalin. Posteriorly the body becomes 

 still thinner, and is narrower toward the extremity. The posterior end 

 is either obtuse or sharply pointed, according to the state of contrac- 

 tion. The posterior opening of the intestine is subterminal. In none 

 of the many specimens obtained was the caudal cirrus present, though 

 such an appendage is probably present in uninjured worms. 



The cephalic slits are moderately elongated, and extend backward 

 as far as the anterior end of the mouth. Their posterior ends are 

 wide and deep, and in life their margins are thin and widely separated. 

 Anteriorly they do not reach quite to the proboscis pore, except when 

 the animal is strongly contracted. 



Color. In life the whole body, both above and below, except the 

 tip of the head, is bright blood red. The anterior extremity is tipped 

 with a narrow band of white or yellowish-white. This white tip ex- 

 tends both above and below, and is not usually more than a few milli- 

 meters wide. The proboscis is light red in color. 



Size. Individuals were most commonly from one to two meters in 

 length, and 8 to 10 mm. in width in the intestinal region. A few of 

 the specimens obtained measured as much as two and a half meters 

 when extended. 



The individuals are generally hardy, and are not so prone to break 

 spontaneously into fragments as are those of many other species of the 

 genus. They contract much less violently than most other Nemerteans 

 when killed, and may consequently be easily preserved entire by kill- 

 ing in a dilute solution of formalin in sea water. 



