458 F. W. GAMBLE AND J. H. ASHWORTH. 



alimentary caual are almost identical with those of A. marina. 

 The cavity o£ the oesophageal pouches is partially subdivided 

 by numerous incomplete septa, produced by infolding of 

 the wall of the pouch. The septa are covered by colum- 

 nar cells; among which are glandular cells. In each septum 

 between the epithelial lamellae is a cavity filled with 

 blood. The gland cells of the stomach are very obvious 

 in all species. There is a well-marked ventral groove, 

 commencing about the middle of the stomach, and con- 

 tinuing backwards to the anus. In the stomach and an- 

 terior part of the intestine there are, opening into this 

 groove on each side, oblique grooves which are situated on 

 the side walls of the alimentary canal, the general direction 

 of which is downwards and backwards. The cells lining all 

 these grooves are ciliated, and produce currents towards the 

 anus. 



The anus is not surrounded by processes or by a special 

 cone-like arrangement as in the Maldanidae, but is merely 

 bordered by simple papillae. 



The exact nature of the food and the mode by which it is 

 extracted from the sand and debris, and rendered available 

 for absorption, are problems upon which we can throw little 

 light. The great abundance of Arenicola wherever the 

 sand, mud, or gravel contains a large proportion of decom- 

 posing matter or sewerage, and its absence from long stretches 

 of coast where the beach is clean sand, show that these 

 animals feed on decaying animal or vegetable matter. 



9. Vascular System (PI. 24, figs. 26,30; PL 25, 

 figs. 44, 45). 

 Milne-Edwards (1838) figured and described the chief parts 

 of the circulatory system of a specimen of A. marina, which, 

 however, possessed only five pairs of nephridia, the first pair 

 being absent. His figures, while on the whole correct, are in 

 error in showing the heart in direct connection with the dorsal 

 vessel. Cosmovici (1880) has also described and figured the 

 vascular system of the anterior portion of this species. He 



