56 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
only notable regional differences le in the epithelium. 
The connective tissue is much the same throughout, and 
is continuous with that of the body-wall in which the diges- 
tive viscera are imbedded. The blood lacune are very 
numerous and communicate on the one hand with the 
cardio-visceral, and on the other hand with the branchio- 
visceral main blood vessels. 
The connective tissue is also penetrated by (a) the ceca 
of the gonads, especially the spermatic tubules, and (0) 
the delicate branched clear tubules of the enigmatical 
refringent organ or pyloric gland (Pl. IV., fig. 7). The 
tubules of this organ are lined by low cubical cells, usually 
non-ciliated, containing no concretions or granules, and 
having no great resemblance to gland cells. They have 
been called ‘“ chylific”’ and absorptive, but the function is 
still undetermined. ‘There are few, if any, muscle fibres 
in the connective tissue of the alimentary canal until the 
rectum is reached. 
The lning epithelium is for the most part ciliated, 
especially in the cesophagus and intestine. The ceso- 
phagus has slight longitudinal ridges and grooves, one 
of which seems to continue the canal of the dorsal lamina 
onwards to the stomach, while another is in relation with 
the posterior fold coming from the lower end of the 
endostyle. There are a few glandular (mucous) cells 
scattered amongst the ciliated columnar cells of the 
cesophageal wall. 
The stomach has projecting folds in its interior which 
unite at its pyloric end to form the intestinal typhlosole, 
and, in addition to some ciliated and mucous cells, it has 
large masses of highly coloured markedly glandular cells 
packed with yellow granules. The intestine, again, has 
ciliated and gland cells, and in the rectum the gland 
cells become fewer and die out. ‘The termination of the 
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