STRUOTUEE OF TWO NEW GENEKA OF EARTHWOEMS. 255 



further back it is suspended by two closely approximated and 

 very delicate mesenteries, which later become continuous with 

 a bridge of tissue, along which blood-capillaries pass from the 

 perioesophageal blood-sinus to the vessels of the pouch. This 

 bridge forms the walls of the aperture of communication 

 between the oesophagus and the pouch. The minute structure 

 of the pouch is as in Hyperiodrilus, but there is no splitting 

 of the muscular layer of the oesophagus at the origin of the 

 pouch, such as I have figured and described in that earthworm. 



The second pouch, which lies in the 13th segment, has a 

 precisely similar origin from the oesophagus, and is identical in 

 all respects with the first. 



In the next segment is a third oesophageal pouch, which is 

 very much smaller than either of the other two ; its interior is 

 not so subdivided by the development of folds, and the aperture 

 into the oesophagus is distinctly larger ; it has the characters 

 rather of a folded-ofi" portion of the oesophageal tube than of a 

 diverticulum. 



After this the tube remains narrower for some distance, with 

 the epithelium longitudinally folded ; it is here, as throughout 

 its whole extent up to this point, lined by a thin chitinous 

 layer; there is, however, no gizzard upon the oeso- 

 phagus, and no special thickening of its muscular 

 coat which could be compared to a gizzard. 



In the 14th segment the oesophagus becomes wider, and 

 receives the ducts of the calciferous glands ; these ducts have 

 exactly the same structure as the oesophagus, and are not of a 

 very greatly inferior calibre. Their epithelium is dis- 

 tinctly ciliated; each duct opens by a wide aperture on to 

 the side of the oesophagus. After the opening of the ducts of 

 the calciferous glands the epithelium of the oesophagus 

 alters its character and becomes ciliated. The dia- 

 meter of the tube is at the same time larger, and the plexus of 

 blood-vessels more richly developed. Commencing with the 

 18tli segment the alimentary canal is provided with six gizzards, 

 one to the 18th and to each of the five following segments, 

 connected by sections of thin-walled intestine. 



VOL. XXXII, PART II. — NEW SER. K 



