Loxogenes arcauum Nickerson. 277 



An exceedingly short gullet follows. This is in marked contrast 

 with B. medians where the oesophagus is very long (Looss, 1894, 

 fig. 36) nearly equalling the length of the intestinal coeca. The 

 intestinal coeca are short and rather wide. They are of equal length 

 and extend posteriorly as far as the level of the gonads, but not as 

 far as that of the ventral sucker. The intestinal epithelium con- 

 sists of very tall and slender cells, these are free from each other 

 laterally, have nucleus at the base, there is in many a clear vacuole 

 at the ends of the cells. 



According to Nickerson's figure of D. arcanum the intestinal 

 coeca are of unequal length, the right one reaching back as far as a point 

 posterior to the posterior limit of the ovary, and as far as the cen- 

 tre of the body, in my series of 250 sections the intestine ends in 

 the 90 th section of the series. The usual muscular coats are found 

 in the wall of the intestine. 



The Excretory System. 



The excretory pore is located (Fig. 4) on the dorsal surface 

 near the posterior end of the body. It opens from a short and 

 narrow tubular passage which soon widens laterally as it runs for- 

 ward and branches to form two wide flattened chambers, the excre- 

 tory vesicles. The coils of the uterus are the only other organs 

 which reach down into this region of the body, they are wholly 

 ventral to the excretory vesicles. In serial sections these vesicles 

 were traced forward, they are closely adherent to the coils of the 

 uterus and lie some distance from the dorsal wall of the body. 

 Anteriorly they can be traced to a point a little behind the posterior 

 border of the testes. The posterior tubular portion of the system 

 is lined with a thick cuticle, this disappears from the wall as it 

 reaches the two vesicles. Posteriorly the cuticle of the median tube 

 becomes continuous with that of the outer surface of the body at 

 the excretory pore. This cuticle is destitute of spines, these ending 

 abruptly as the pore is reached. 



The outer end of the passage is surrounded by a remarkable 

 sheath of cells (Fig. 4). The sections show that these cells are a 

 continuation of the sub-cuticular cells ; similar cells are indicated in 

 Nickerson's figure. 



The walls of the vesicles are made up of very much flattened 

 cells whose nuclei are plainly visible, and there are in addition musculai' 

 fibres. Since there are no cilia in the walls of the vesicles we must 



