NEMERTEANS 



255 



Lineus longifissus (Hubrecht). 



Cerebratulus longifissus, Hubrecht, 1887. 



One hundred and thirty-four fragments including eleven heads and four tails were 

 preserved at St. 167 (N 81, N 81 a). Fourteen complete worms were examined later. 

 They had been caught in another net at the same station. 



Two worms were reconstructed from reddish backed fragments giving approximate 

 lengths of 7-0 cm. The breadth and depth were 07 and 0-35 cm. respectively. 



The colour of the spirit specimens is reddish or greyish on the back and pale grey or 

 white beneath. The body is flattened, anterior end more cylindrical than posterior, and 

 the tail is pointed. The surface of the skin shows slight circular wrinkling especially 

 anteriorly. As remarked by Hubrecht the mouth is small and the cephalic slits very 

 long. They become shallower gradually, but appear much more sharply cut than in other 

 Lineids. The following measurements were made of complete worms and fragmented 

 heads. 



I can add the following notes to the account given by Hubrecht. Frontal organs are 

 present. Head glands are diffuse, stain with haematoxylin and do not reach the anterior 

 end of the brain. The small cephalic canals pass from the fissures just after the level of 

 the ventral commissure. Before they penetrate the brain a dorsal branch is given off 

 by the dorsal ganglion. This branch is extremely short. The posterior lobes of the brain 

 lie in a blood sinus. 



One of the characters of the species is the very marked power of autotomy. 



Lineus roseocephalus, n.sp. (Plate XVI, fig. 24). 



With the dark brown L. corrugatns collected under stones in the harbour of Port 

 Stanley, Falkland Islands, was this light red form represented by a single specimen 

 (N 22) 45-0 mm. long and about i-o mm. in diameter. In addition to the colour, dif- 

 ferences from L. corrugatus were readily perceptible in the tapering shape of the body 

 and the rounded anterior end. No mouth was visible but the cephalic slits were very 



