^yS H. F. MOORE. [Vol. X. 



genital openings. Running from somite XIII to XVI, or 

 XVII, we find a strip of clitellar tissue lying between the dor- 

 sal and ventral couples of setae. The coarsely granular cells 

 of the clitellum are not represented in this region, which, 

 moreover, is quite detached from the clitellum proper, the 

 hypodermis of somites XVIII to XXII being unmodified. 

 Not a little of the swelling in the genital region is due to this 

 increased hypodermal thickness. 



Alimentary caiial. — The alimentary canal is quite highly 

 specialized and differentiated into well-marked regions. 



The buccal chamber lies in the first two somites. Its lining 

 epithelium is columnar, with oval nuclei near the free end of 

 the cells; it is connected with the body- wall of the first two or 

 three somites by irregular, radiating muscle-bands, derived 

 from the longitudinal muscle-layer of the body-wall. Other 

 than this the musculature is slight, the circular layer of enteric 

 muscles consisting of but a few scattered fibres. 



Succeeding the buccal chamber is a well-marked pharynx 

 occupying about two somites, but appearing to be much more 

 extensive, owing to the great displacement of the septa. 

 Owing to inequalities in the depth of the cells of the epithelial 

 lining, the latter in its ventral and lateral regions is thrown 

 into ridges and papillae. Upon the dorsal wall, or roof, of 

 the pharyngeal sac, the epithelium is of quite different appear- 

 ance. The cells are of uniform depth, more slender and with 

 a more elongate nucleus; moreover, they are furnished with 

 cilia, whilst the other cells of the pharyngeal region are non- 

 ciliated. 



The dorsal and lateral walls of the pharynx are covered in 

 by a dense mass of muscle, blood-vessels, and glandular appear- 

 ing cells. The latter are especially abundant in somites IV, 

 V, and VI, where they are aggregated into paired masses. In 

 somites IV and V the respective pairs are united in the middle 

 line, but in somite VI the masses are much smaller and are 

 confined to the sides of the oesophagus. I have been unable 

 to find any communication between these cells and the lumen 

 of the canal. Similar masses of tissue surround the pharynx 

 in other genera of earthworms. 



