NEMERTEANS. 103 



The epithelium is, for this genus, very high (PI. IV. fig. 15) and is marked by two 

 rows of nuclei — one near the base of the epithelium and one about the middle. In the 

 outer portion of the epithelium occur a few rhabdite-like structures which take a bright 

 yellow hue with picric acid. This epithelium rests upon a thick basement membrane which 

 is more than half the thickness of the epithelium itself. 



A delicate circular muscle layer lies just beneath the basement membrane and is less 

 than half the thickness of this latter structure. A thicker longitudinal muscle layer lies 

 beneath the circular layer. Beneath this layer again there is in the oesophageal region an 

 inner very delicate layer of circular muscles (PI. IV. fig. 16 7nci), which is well marked 

 on the ventral surface of the oesophagus, and which is continued laterally to enclose the 

 two lateral blood vessels. On the dorsal surface of these the fibres end. Between the 

 proboscis sheath and the alimentary canal there is a delicate layer of longitudinal muscles 

 both in the oesophageal and the intestinal regions. 



The vascular system is extremely simple as in the other members of the genus. There 

 are two longitudinal lateral vessels which unite together over the rhynchodaeum anteriorly. 

 In the oesophageal region these vessels are exceedingly spacious. They are lined by a 

 delicate flattened endothelium. They do not extend to the proboscis sheath. 



The mouth is situated on the ventral surface directly beueath the brain. Its hinder 

 termination is at a level slightly in front of the hind end of the brain. The oesophagus 

 is short and passes directly into the intestine, which can be readily distinguished by the 

 absence of gland cells in its epithelium. It possesses small lateral diverticula. 



The proboscis is exceedingly fine, not exceeding -16 mm. in diameter. It possesses a 

 longitudinal muscle layer and an exceedingly delicate circular muscle layer just beneath the 

 proboscis epithelium. The proboscis sheath possesses an extremely fine inner longitudinal 

 and a somewhat thicker outer circular muscle layer. The rhynchocoelom is small. 



There is no trace of nephridia. 



The nervous system is poorly developed. The brain is small and the ventral ganglion 

 is as large as the dorsal. The ventral commissure is fairly stout — the dorsal commissure 

 is weak. Through the nervous ring thus formed pass proboscis sheath and blood vessels. 

 The oesophageal nerves are well marked. A well marked median dorsal nerve is present 

 between the basement membrane and circular muscle layer. There is also between these 

 two layers of the body wall what appears to be an exceedingly delicate layer of nerve 

 fibrils, and minute twigs may be observed piercing the basement membrane to reach the 

 epithelium above. 



There are no special sense organs, frontal organ, eyes, and cerebral organ being all 

 absent. Moreover there are no traces of cephalic slits. There are no head glands. 



The single individual procured is a female and the ovaries extend into the hinder 

 oesophageal region. They lie rather dorsal to the level of the nervous side stems (PI. IV. 

 fig. 16), and to the outer side of the blood vessels into which they project. The cavity 

 of the ovary is only separated from that of the vascular system by the delicate endo- 

 thelium of the latter. No gonidial ducts are developed. The ova are apparently not yet 

 mature. 



