MARIONELLA 355 



and farther apart, but also to the fact that one-third of the circumference 

 is destitute of denticles, namely that part of the circumference opposite 

 the large onchium. In this particular region, however, the'interior walls 

 of the pharynx are very finely longitudinally striated. The back row of 

 denticles, it should be pointed out, is on the wall of thfe posterior half of the 

 pharynx. 



The neck is conoid, or occasionally subcylindroid, and ends in a cylindroid 

 or, more often, a rather decidedly convex-conoid head. 



Amphids and eye-spots. Though the amphids are well-developed, they 

 are rarely plainly to be seen. Their exterior expression consists of two dor- 

 sally sub-lateral concavities two to three times as wide as long, impinging on 

 the bases of the lateral setae. Though the peripheries of the amphids may 

 seem to be closed, they are, in fact, nearly always found to be open on the 

 posterior margin near the lateral fields. As a rule their contours are almost 

 invisible, so that their form and extent are mainly indicated by the apparent 

 absence in them of the fine structural elements to be seen elsewhere in the 

 cuticle of the head. When clearly defined, their contours are found to be 

 reniform with the convex side forward. They are located on or near the 

 base of the lip-region, and more or less opposite to the rows of denticles. 

 They are usually one-third to two -fifths as wide as the corresponding diameter 

 of the lip-region and two to three times as wide as long. 



More often than not two eye-spots are present. These take the form of sphe- 

 roidal, compact collections of about one hundred brownish granules, each 

 collection lateral in position and lying between the oesophagus and body- 

 wall, being about one-fourth as wide as the corresponding portion of the 

 neck, and removed from the anterior extremity by a distance two to four 

 times as great as the width of the head. Anteriorly, these ocelli often present 

 a spherical cavity in which there is at least the suggestion of a spherical 

 lens. 



Oesophagus. The simple conoid oesophagus is destitute of bulbs and 

 receives the base of the pharynx in its anterior extremity, where it is usually 

 about half as wide as the base of the head. Near the nerve-ring it is usually 

 about one-half, and posteriorly usually about three-fifths, as wide as the 

 corresponding part of the neck. It is always separated from the intestine 

 by a distinct cardiac collum about one-third as wide as the base of the neck. 

 While not conspicuous, the lining of the oesophagus is a distinct feature 

 throughout its length. Though the oesophageal musculature is usually 

 fine, the structure is occasionally coarse in the posterior part. Rarely, 

 yellowish spherical granules are found in the tissues of the oesophagus. 

 The oesophageal glands are well-developed, or at least one of them is; as 

 before stated, they empty into the pharynx through pores in the onchia. 

 The right submedian gland is without exception the largest. There is us- 

 ually a well-developed conoid or hemispherical cardia one-third to one-half 

 as wide as the corresponding portion of the neck. 



Intestine. The intestine becomes at once one-half to two-thirds as wide 

 as the body, and is made up of cells of such a size that few are required to 

 build a circumference. Its walls are thick, and its lumen faint. Its cells 

 invariably contain fine spherical granules of more or less variable size, the 

 largest of them being one-fortieth to one-twentieth as wide as the body. 

 The granules are scattered, or sometimes numerous, in the cells, and may 

 be so arranged as to give rise to a faint tessellated effect, though this is unusual. 



