HERPOMENIA PLATYPODA. 153 



lar groove between it and the muscular pharynx. Through the posterior wall of 

 this groove the ventral salivary glands find their outlet by means of two ducts 

 very closely situated to the mid line (Plate 8, fig. 1, Plate 19, fig. 8). 



The ventral salivary glands are unusually large organs completely encircling 

 the gut for part of their course, and occupying most of the space between it and 

 the body wall from their outlet to the junction of the pharynx and stomach- 

 intestine. The cells composing them are pyriform, 0.024 mm. in greatest diame- 

 ter and are filled with a homogeneous, moderately staining secretion in which 

 the relatively large nucleus holds a more or less central position. The cells are 

 arranged in lobules, and their delicate ductules open by intercellular channels 

 (Plate 19, fig. 13) on each side of the body into a reservoir whose superficial extent 

 is much increased by several folds. The outlet from each reservoir passes to a 

 small diverticulum of the pharyngeal wall into which it opens opposite its fellow 

 and very close to the median plane. 



The pharynx is a prodigiously heavy tube whose walls are composed of a 

 compact mass of muscle fibres chiefly circular (Plate 19, fig. 7) lined with high 

 columnar cells developed into upwards of a dozen longitudinal folds. These 

 last named elements contain a weakly staining secretion and are in contact 

 distally with a distinct cuticular membrane. Posteriorly this tube projects 

 some distance into the stomach-intestine, Plate 8, fig. 1. A radula is completely 

 lacking in this species, and it is probable that, as in Drcpanuinenia vampyrella, 

 the secretion of the salivary glands exercises a solvent action on the tissues of the 

 host that are then sucked up by the powerful pharynx though its exact mode of 

 operation is difficult to understand. Nettle cells, from the host, are present in 

 the intestine, in some cases seemingly imbedded in the epithelial cells. 



The lining of the stomach-intestine, where the distal portions of the cells 

 bearing the secretion have not been detached, is excessively high, in one specimen 

 almost occluding the lumen. Beneath the gonad is a small median fold appar- 

 ently ciliated, and showing evidence of slight glandular activity. Ventral to the 

 pericardial cavity the gut rapidly narrows to an almost circular tube of small 

 calibre and opens with the shell gland into the cloaca. 



The pericardial cavity, as may be seen (Plate 8, fig. 3), is of moderate size 

 only, and is in large measure filled by the simple tubular heart. The aorta is 

 exceptionally small as are the sinuses generally with which it connects, yet so 

 far as they have been traced their relations appear to be perfectly normal. 



The gonad holds the customary position, but is remarkable in several 

 respects. In the first place it is sharply differentiated into two zones in the two 



