114 W. F. U. WELDON. 



neither is there any sign of a division of the cavity by trans- 

 verse septa. 



In certain of the connective-tissue cells which thus traverse 

 the body cavity are "flame cells" belonging to an excretory 

 system of the ordinary platyelminth type. The granular and 

 opaque character of the ectoderm made it extremely difficult to 

 observe these organs in the living animal, and I did not succeed 

 in finding them in sections. I can only say that there is cer- 

 tainly a group of ''flame cells" at the points marked ne. in 

 fig. 1. 



The alimentary canal presents all the well-known 

 characters distinctive of the genus. The mouth (fig. 1, m) is 

 an elongated slit bounded by curved, ciliated lips. It leads 

 into an upwardly-directed pharynx, which communicates ante- 

 riorly by a narrow opening with the oesophagus. The oeso- 

 phagus itself passes horizontally backwards. The section 

 represented in fig. 4 is taken immediately behind the point of 

 communication between these two structures, so that the oeso- 

 phagus [os.) is here entirely shut off from the pharynx [v. ph.). 

 The pharynx itself is seen to be a bounded vertical wall, com- 

 posed of pale, columnar, ciliated cells ; outside these lie masses 

 of gland-cells [m. g.), which are in places closely attached to 

 the pharyngeal epithelium ; other similar gland-cells (e. gl.) 

 lie at the base of the ectoderm of the lip. 



A section or two further backwards (fig. 5) the pharynx is 

 seen to be composed of two portions — a main vertical portion, 

 the same as that seen in front, and a horizontal portion {h.ph.), 

 in the form of a lateral pouch on each side. In this, as in the 

 preceding section, groups of gland-cells are seen, attached both 

 to the pharynx and to the oesophagus. 



Passing on to the region behind the mouth, the epithelium 

 of the vertical portion of the pharynx becomes darker and 

 streaked with bands of mucus thrown into it by the glands, 

 which still surround it (fig. 6). The ventral pouches have now 

 united to form a horizontal limb below the main body of the 

 organ, so that its lumen becomes j.-shaped. Finally, still 

 further backwards, the vertical portion ends in a large muscular 



