556 R. C. PUN NET!'. 



about 3 — 4 mm. apart. Head shaped like a spear-head, but 

 not quite as wide as the succeeding portion of the body. It 

 is very flat, as is the animal throughout, especially the 

 posterior part of the body, which is almost oar-like. When 

 squeezed the brain was noted as a small yellowish mass in 

 front of the mouth opening. The gonads were regularly 

 arranged. The proboscis extended over nearly half the 

 length." On preservation the anterior portion becomes 

 cylindrical, though the posterior ha.lf of the body remains 

 somewhat flattened. 



The epithelium is not high. It is crowded with nuclei, 

 and contains a number of unicellular glands which stain 

 vividly with picric acid. There is a fine but well-marked 

 basement membrane in the oesophageal region, beneath which 

 is a well-developed layer of circular muscle-fibres (fig. 17). 

 Underneath this again is a thick layer of gelatinous-like con- 

 nective tissue, which stains deeply with nigrosin, though 

 faintly with carmine, thionin, or picric acid. It contains a 

 number of small glands (fig. 15) whose contents stain deeply 

 with thionin, and whose secretion can, with the help of this 

 reagent, be traced through the epithelium The layer bears 

 some resemblance to the gelatinous connective-tissue layer 

 found in Eupolia, though in that genus the cutis glands are 

 aggi'egated neater the outer surface. In the intestinal region 

 the basement membrane disappears, the cutis glands become 

 smallei'j and the connective-tissue layer more fibrillated in 

 appearance. The epithelium of the circular head groove is 

 characterised by the absence of the unicellular glands and the 

 rich ciliatiou. 



The muscle layers of the body-wall are well developed. 

 The internal longitudinal layer is thicker than the circular. 

 In the oesophageal region it forms a well-marked layer dorsal 

 to the alimentary canal, between the latter and the proboscis 

 sheath. It is also continued dorsally round the proboscis 

 sheath, completely separating the latter from the circular 

 muscle layer. The outer longitudinal muscle layer is con- 

 siderably thicker than either of the other two. There are no 



