28 R- C. Punnett, [No. 2 



External features. A short and somewhat stoutly built form in 

 comparison with otlier members of the genus. Much flattened 

 in shape. The larger of the two specimens obtained measured 

 after preservation in formol 22 cm. with an average breadth 

 of 4 mm. The breadth was somewhat greater in the oesophageal 

 region, and rather less towards the hind end. The worm is 

 remarkable from the presence of two deep longitudinal depressi- 

 ons' on the dorsal surface of the head (Pl. I, fig 3). Colour 

 pure white throughout with a semi-transparent appearance. 



Body wall. The epithelium is high but apparently completely destitute 

 of unicellular glands. The basement membrane is w T ell marked 

 and is about double the thickness of the underlying circular 

 muscle layer. The longitudinal muscle layer is comparatively 

 feeble not being thicker than the epithelium. It is rather more 

 developed on the ventral than on the dorsal surface. Inside 

 the body wall the gelatinous connective tissue is exceedingly 

 abundant, and in it lie imbedded the nervous side stems, the 

 lateral blood vessels, and the excretory tubules all widely 

 separated from one another. Numerous small strands of muscle 

 fibres cross it in various directions. 



The proboscis is small and slender. 16 proboscis nerves are present. 

 Unfortunately the armature, as is not unfrequently the case 

 with specimens preserved in formol, has been dissolved out. 

 The proboscis sheath extends only through the anterior 1 /z of 

 the body. Rhynchodaeal opening subterminal and ventral. 



Alimentary canal. The mouth opens into the rhynchodaeum only 

 just in front of the level where the proboscis takes its origin. 

 Hence in the precerebral region a single canal alone is seen 

 in section. After its junction with the intestine the oesophagus 

 is continued backwards for a short distance as a blind diverti- 

 culum provided with small pouches. The blind gut does not 

 reach forwards as far as the brain. 



The vascular system is formed on the usuai metanemertean type. 



The excretory system, like that of other members of the genus reaches 

 back into the intestinal region. Anteriorly the tubules do not 

 reach as far as the brain. A single duct is found on either 

 side near the anterior end of the system. The duct passes 

 just over the nerve stem and comes to op en by a pore on 

 the ventral surface. The tubules are scattered diffusely through 

 the gelatinous tissue and never come into close contact with 

 the blood vessels. 



