131 



ward, diverg-ing- only slightly up to the point where they begin to 

 pass around the digestive tract. Near this point these trunks divide, 

 gixing" rise to a pair of branches which continue on into the pro- 

 stomiuni. The main pair of trunks extend around the digestive tract, 

 forming the circumoesophageal commissures, uniting again on the 

 \-entral side to form the suba?sophageal ganglion, which lies partly 

 in I and partly in II. 



Pcptoncphridia. — Two peptonephridia are present, one arising 

 from the dorsal and the other from the ventral side of the digestive 

 tract in the anterior part of V. Both extend caudad and adhere 

 closely to the alimentary canal, and for a considerable part of their 

 extent lie between the epithelial layer and the muscular coat of the 

 latter. Each is composed of two strands which give off at intervals 

 a number of tubules that project freely into the coelom. In VI both 

 the dorsal and ventral ])eptonephridia become greatly tliickened and 

 enlarged. Near this enlargement the ventral peptonephridium gives 

 rise to a number of tubules which extend around the digestive tract 

 on either side. The terminus of each tubule is in the immediate vi- 

 cinity of the dorsal vessel. They come into close proximity to the 

 dorsal strands but so far as observed do not unite with them. After 

 giving off these tubules the strands become reduced to their former 

 size and so remain as far as VII, where the ventral peptonephridium 

 becomes thickened again and gives rise to tubules which project freely 

 into the body cavity. These tubules resemble those in VI in general 

 structure but differ in being shorter and fewer in number. They ex- 

 tend dorsad on each side of the digestive tract, but do not reach the 

 dorsal surface. Both peptonephridia end immediately anterior to the 

 intestinal diverticulum, in the posterior part of VII. 



Taste Organs ("Gcschiuacksldppchc]!"). — This species is some- 

 what unique in having four of these organs (PI. VIII, Fig. 8) in- 

 stead of the usual number, two. They extend from the floor of the 

 buccal cavity, and are products of the lining epithelium and structur- 

 ally like it. These tongue-like organs are sometimes directed caudad, 

 sometimes cephalad, the direction depending on the state of retraction 

 of the pharynx. Four muscle strands, two on either side of the 

 median line, are attached to the wall of the buccal cavity at the bases 

 of these organs and extend obliquely ventro-caudad to the body wall. 

 Vejdovsky ('84, p. 99) describes ganglion cells in the bases of the 

 "Geschmacksliippchen" which he studied, but the}' ha\'e not been seen 

 in this species. 



Intestinal Dvuerticidum. — At the junction of the intestine with the 

 CESophagus, in VIII, there arises a structure which is reflected cephalad 



