coe: nemerteans of west and nokthwest costs. 133 



epithelium consists of columnar ciliated and glandular cells as in 

 related genera. The glandular cells are of two or more varieties, 

 forming different kinds of secretions (PI. 9, fig. 60). Certain cells, 

 as in other species, form homogeneous, rodlike masses of apparently 

 semisolid consistency, while others secrete a deeply staining gran- 

 ular substance. Interspersed among these are numerous clear, 

 mucous cells. 



Conspicuous among the epithelial cells when examined with high 

 powers of the microscope are numerous extremely delicate fibers 

 which pass from the underl\dng tissues thi'ough the basement mem- 

 brane and ramify among the integumental cells. These delicate 

 fibers are most numerous in the head and anterior esophageal 

 regions, although they are found throughout the body. It seems 

 not unlikely that a small portion of them are nerve fibers, and that 

 the}^ communicate peripherally with specialized sensory cells in the 

 integument. 



On the other hand, it can be readily demonstrated that the major 

 portion of them are muscular fibers, for they can 1)6 followed through 

 the basement layer and into the outer circular muscular layer where 

 many of them undoubtedly originate. In favorable preparations cer- 

 tain of the fibers of the muscular layer can be seen to thus branch 

 off to the integument. Such integumental fibers have been de- 

 scribed for several other species of nemerteans, and are especially 

 common in the Paleonemertea. It seems probable that from some 

 such loose arrangement of fibers as is here found, the definite layers 

 of integumental muscles of Carinoma and higher forms have been 

 derived. In Caeinoma a portion of the fibers are always loosely 

 arranged. 



The specialized epithelium of the contractile lateral sense organs 

 will be considered below (p. 142). 



The differentiated portion of the integument which constitutes the 

 dark, brownish band so conspicuous in preserved specimens, as de- 

 scribed above (p. 128), exhibits the same peculiarities as the similar 

 bands in Carinella. In all stained preparations the anterior line 

 of demarcation of this band is sharplj' distinct. The peculiarities of 

 the integument in this region are apparently due to a great abun- 

 dance of specialized gland cells, which are situated among the ordi- 

 nary integumental cells, and which form a secretion of such a chemical 

 nature that it is in some way decomposed by the action of the pre- 



