220 PRONEOMENIA ACUMINATA. 



The first of these concerns the anterior dorsal coecum, which extends as far 

 forward as the brain. Throughout its entire course it is dorsoventrally com- 

 pressed, and is totally devoid of pouches though its lining epithelium resembles 

 that of the stomach-intestine. Ventral to its base (Plate 5, figs. 1, 2) is a much 

 smaller, anteriorly directed coecum similar, in the character of its fining cells, 

 muscular sheath and folds, to the pharynx with which it is directly continuous. 

 Finally the pharyngeal epithelium extends along the ventral side of the digestive 

 tract as far as a dorsoventrally compressed ventral coecum whose cells are 

 identical \vith those of the stomach-intestine. It is thus apparent that the 

 pharynx or oesophagus dilates posteriorly into a fumiel-shaped structure and 

 in this form unites with the stomach-intestine. 



The stomach-intestine, with its lateral sacculations, dorsal ciliated tract, 

 and lining of digestive cells, presents no especially noteworthy features. As it 

 passes between the limbs of the gonoducts it becomes triangular, then more or 

 less elfiptical as it crosses the undivided section and finally as an almost circular 

 canal it opens into the cloaca. 



The cloacal chamber is of moderate size only (Plate 5, fig. 5), and its plain 

 or only slightly folded walls exhibit no especial pecuUarities though it may be 

 said that the cells forming the lateral walls are heavily cifiated. Undigested 

 material, associated with some darkly staining secretion, fills the cavity with 

 the exception of that held by a parasitic or commensal worm, apparently a 

 rhabdocele. 



The condition of the present specimen incUcates that the breeding season 

 was close at hand, as the gonad is greatly distended with sex products and the 

 gonoducts are in a condition of great glandular activity. The reproductive 

 gland, distinctly paired throughout, extends anteriorly as far as the level of 

 the radula, and on the other hand unites, as usual, with the front end of the 

 pericardial cavity. With the extreme forward tip of each division of the gonad 

 the organ is filled laterally with male products, in all stages of development 

 while large numbers of what appear to be nearly mature ova attach to the 

 wall along the mid line. 



Posteriorly the conditions are peculiar. The halves of the gland diverge 

 widely until in the region of the pericardium they are separated by a space 

 nearly equal to one third the diameter of the body. This intervening space 

 is spanned dorsoventrally by muscle fibres, and is filled with blood corpuscles 

 and furthermore is directly continuous with the heart so that it is doubtless a 

 greatly expanded aorta. Close to the posterior end of each half of the ovo- 



