16Q Transactions of the Royal Society of Victoria. 



against the burrow walls, and renders it difficult to extract 

 the worm from its hole. The posterior end especially seems 

 to have a strong power of suction. 



Alimentary Canal. 



The mouth is overhung by the ridged prostomium, and 

 leads into the strong muscular phar3mx, extending back to 

 the 5th segment. 



There is a good development of salivary glands which 

 microscopically appear to resemble nephridia in structure. 



The 5th segment contains the short oesophagus and longer 

 gizzard, then follows the long intestine which, in segments 

 12 to 18, contains a series of very vascular dilatations, and 

 from the 19th runs backwards to the terminal anus. Its 

 walls are very distinct, yellow-brown in colour, and consist 

 internally of an epithelium of deep cylindrical cells, with 

 large nuclei and nucleoli, external to these a layer of circular 

 muscle fibres, then a series of longitudinal fibres, and then 

 a layer of cells whose thin internal ends send processes 

 between the longitudinal fibres, and perhaps deeper still 

 whilst their external parts are filled with yellow-brown 

 granules. The cells contain large nuclei, and are to be 

 regarded simply as modified cells of the membrane lining 

 the body cavity. There is no structure present representing 

 the t3rphlosole. 



Nervous System. 



This resembles that of the ordinary worm, save that the 

 distinction into ganglia and connecting commissures is not so 

 clearly marked. Sections show clearly its double nature, 

 and the arrangement of the large ganglion cells on the 

 ventral and lateral aspects, and of the fibres in a double 

 longitudinal band dorsally and internally. Dorsally are 

 three, and at times, even four, of the so-called giant-fibres 

 present. Each one, however, is very distinctly not hollow, 

 but has the form of a solid homogeneous rod, surrounded by a 

 considerable amount of ensheathing connective tissue. Three 

 pahs of lateral branches pass ofi" in each segment, and m 

 sections can be traced towards the surface till they spread 

 out on the internal side of the circular muscles in the body- 

 wall. 



