ON MONOPYLEPHi RUS LIMOSUS. 



n.pt 



consists of a syncytial tissue with a cytoplasm more compact 

 than that of the peritoneal cells. 



5). The peritoneal 

 layer is especially well 

 developed in the anterior 

 part of the body and con- 

 sists of large vesicular cells. 

 In the part anterior to the 

 clitellum the peritoneum 

 ^consists mostly of pear- 

 shaped cells, with their 

 rounded ends directed to- 

 ward the cœlom and 

 giving rise to an irregular 

 surface, while in the more 

 posterior part it presents 

 in general a smooth sur- 

 face, being composed 

 mostly of irregularly shap- 

 ed cells. The nuclei are 

 large and sometimes nu- 

 cleolated. 



Some glandular cell- 

 masses, always richly supplied with fine blood- capillaries, occur 

 attached to the peritoneum in segments IV and V, often in III. 

 These cells appear to be differentiated from the peritoneum and 

 contain each in its cytoplasm many large, secretory granules, which 

 stain deeply with hematoxylin. In sections these cell- masses are 

 very conspicuous owing to their deep staining, and are mostly found 

 on the ventral side of the dorsal setal lines, projecting into the 

 cœlom. I have found in these cell- masses one or two cells (fig. 3, 



n.hp lm 



Fig. 3. 



Cross section through the body wall of segment IV, 

 showing a glandular cell-mass. x700. s.c — glandular 

 cells, n.s.c — nucleus of glandular cell, b.v— integument- 

 ary blood-vessel, 1.1 — lateral line, cm — circular muscle 

 layer, lm — longitudinal muscle layer, pt — peritoneum, 

 n.pt — nucleus of peritoneal cell, c — cuticle, hp — 

 hypodermis, n.hp — nucleus of hypodermal cell, a — cell 

 of uncertain nature. 



