COE : NEMERTEANS OF WEST AND NORTHWEST COASTS. 1 5 



especially in Drepanophorus, Pelagonemertes, and certain spe- 

 cies of Amphiporus, and in Malacobdella. 



In the Heteronemertea the parenchyma is miich reduced in the 

 head region, and is better developed between the intestinal lolies 

 than in any other portion of the body, but is nowhere very abun- 

 dant. 



The genital glands develop in this parenchyma, and when fully 

 mature occupy nearly the whole of the space in the intestinal region 

 between the intestine and the body walls, or between adjacent 

 intestinal lobes where these are developed, so that at the time of 

 sexual maturity the parenchyma is greatly reduced in amount and 

 extent. 



• The elements of which the parenchyma is composed consist of 

 small, irregularly branched cells (PI. 20, fig. 124) and a relatively 

 vast amount of gelatinous secretion. The branching cells have 

 small oval nuclei and their processes ramify throughout the gelati- 

 nous secretion in which they are imbedded, often uniting together, as 

 Montgomery ('97, p. 14) has so fully described for Cerebratulus, 

 and thus forming an irregular network. The cell bodies are com- 

 monly filled with vacuoles and granules of various sizes, and exhibit 

 the greatest variation in size and shape (PI. 20, fig. 124). 



The protoplasmic boundaries of the cells are often so faintly 

 marked that it is impossible to determine the exact extent of the 

 cell body. 



In life the parenchyma is almost perfectly transparent, and in the 

 pelagic nemerteans is said to resemble the jelly of the Medusae.^ 



Cephalic and t^uhmuscidar Glands. 



Cephalic glands. — In nearly all species of nemerteans one or 

 more groups of specialized gland cells are situated in the cephalic 

 tissues, and open either by a single or by numerous ducts on the tip 

 of the snout. 



These cephalic glands resemble the compound cutis glands in 

 general structure and in their behavior towards stains, showing 

 great affinity for haematoxylin. They are, as a rule, especially well 

 developed in the Iloplonemertea, and in some forms, Carcinone- 

 mertes epialti, for example (Text-fig. 9), occupy the greater bulk of 

 the tissues of the head in front of the brain. 



1 For further details, see Montgomery ("97), and Burger ('95 and '97- :03). 



