ON MONUrYLEPHOEUS LIMOSUS. 



15 



--- il 



the nucleus is ovoid or fusiform, being stuated mostly in the 

 proximal half of the cell. 



The pharyngeal glands are well developed and are arranged in 

 four longitudinal rows on the dorsal side of the pharynx, reaching 

 from the end of the second segment to the anterior face of the 

 first septum (III/IV). The median pharyngeal glands on either 

 side of the dorsal median line are attached to the wall of the 

 pharynx by their whole length ; their anterior portions are narrow, 

 but the posterior are swollen. 

 The lateral glands begin anterior- 

 ly at the same level with the 

 median and lie close on the 

 outside of the latter on the 

 dorsal side of the pharynx. 

 The glands are thicker anteriorly 

 and gradually become slender 

 toward the posterior, and the 

 posterior one- third is detached 

 from the pharyngeal wall, the 

 free end being slightly directed 

 toward the ventral side of the 

 body. In fully contracted 

 worms the pharyngeal glands assume a 4 -palmate shape, as seen 

 from the dorsal side (fig. 15). 



Each gland consists of a compact mass of pear-shaped cells, 

 enveloped by a thin peritoneal connective tissue layer, containing 

 very fine blood -capillaries. Each gland cell has a somewhat granu- 

 lated cytoplasm and a large nucleolated nucleus in the distal half, 

 and its proximal end is" prolonged into a dnct, which either unites 

 with others coming from neighbouring cells or opens directly into 

 the pharyngeal cavity through the interspace between the endodermal 



--sb 



Fig. lO. 



Cross section through the posterior part 

 of segment III, to show the position of the 

 pharyngeal glands . xl50. Cœlomic corpuscles 

 are not shown, pg — pharyngeal glands, 1.1 — 

 lateral line, v.v — ventral vessel, n.c — ventral 

 nerve cord, sb — seta-bundle. 



