122 R. 0. I'UNNETT. 



LlNEIDJC. 

 Cerebratulns nataiis, n. sp. 



Five specimens of this worm were procured from shallow 

 water during the night time by the use of the tow-net. Mr. 

 Bedford informs me that he has observed what was probably 

 the same species swimming with eel-like movements near the 

 bottom during the day time. 



C. natans is from 8 — 10 cm. long. The anterior 2 cm. are 

 rounded and about 4 mm. in diameter. Posteriorly it becomes 

 much flattened dorso-ventrally, and the width increases to as 

 much as 8 mm., which is about six times the depth at this 

 portion of the body, A caudal appendage is present (fig. 11). 

 The snout is blunted, and is marked by a black patch above 

 and below the proboscis pore (fig. 12). Mr. Bedford informs 

 me that in life dorso-lateral longitudinal reddish lines were to 

 be seen. As there is no trace of pigment to be seen in this 

 region after preservation, either in the epithelium or the 

 cutis, it is probable that such an appearance was due to the 

 coloration of the intestinal pouches viewed through the pale 

 whitish-brown integument of the living animal (cf. Verrill 

 [8], p. 435). The head slits are well marked, and are about 

 2"5 mm. in length. The mouth commences rather before 

 the posterior end of the head slits, and is about 2'5 mm. long. 

 A shallow ventral groove runs along the flattened portion of 

 the body, commencing about 15 mm. from the anterior end of 

 the worm (figs. 11 and 15, vgr.). 



The cutis in the oesophageal region shows a well-marked 

 nervous layer directly beneath the epithelium (fig. 21, nep.). 

 Below this is found a thin layer of circular muscle fibres 

 (wcc). The longitudinal muscle layer of the cutis is very 

 highly developed, and in it are imbedded the large cutis 

 glands {cgl.), which have a strong affinity for staining re- 

 agents such as carmalum. The connective tissue layer (cu.) 

 is fairly well developed though it is to a great extent invaded 

 by fibres from the external longitudinal muscular coat {mlo.).\ 



