ZOOL.— Vol. III.] HEATH— EPJ DELL A SQUAMULA. 115 



discharge of their secretion (fig i^,k). In addition to these, 

 there are a small number of gland cells containing relatively 

 coarse granules which remain unstained when treated with 

 iron-hasmatoxylin. In most cases their ducts are likewise 

 difficult to determine, but when filled with secretion they 

 maybe traced directly to the pharyngeal cavity (fig. 17, r). 



Ganglion cells also occur in various positions in the 

 pharynx and the terminal cells of branches of the excretory 

 system. Circular and radial muscles are also well de- 

 veloped, and occupy positions adequately shown in fig. 17. 

 Among these elements of the pharynx are a few relatively 

 small spherical nuclei whose exact nature it is difficult to 

 determine. In macerated specimens they appear to belong 

 to slender columnar cells which occupy interstices between 

 the gland cells, and are apparently supporting cells. 



The oesophagus, with which the rounded posterior ex- 

 tremity of the pharynx connects, is relatively very short and 

 insignificant, serving chiefly as a point of entrance for the 

 salivary glands. The latter consist of a multitude of dis- 

 tinct cells arranged in two groups (fig. 12, 5), each of which 

 extends in a rough way from the hinder border of the phar- 

 ynx, the prostate gland, the ootype, and the anterior end 

 of the reservoir of the excretory system, to a line some dis- 

 tance within and parallel to the margin of the body. Each 

 cell is pear-shaped in outline, with its pointed end continu- 

 ous, with a slender duct which leads, usually by a fairly 

 direct route, to its separate outlet into the oesophagus. 

 Some of the cells contain clear vesicular nuclei, while in 

 others they are relatively small and dense. In almost every 

 case the cytoplasm is loaded with a coarse granular secre- 

 tion, which has a great affinity for logwood dyes. 



The intestine of ^. squaniula is of the usual bifurcated 

 type in which the two main branches are connected pos- 

 teriorly by a commissure. The main system gives rise to a 

 considerable number of minor branches, which after fork- 

 ing repeatedly end blindly among the tissues of the body. 

 Along the median line several of the smaller twigs appear 



