BY E. J. GODDARD. 



329 



lining epithelium, and an outer mass of longitudinal muscle fibres. 

 The main differences in the constitution of the walls of the pro- 

 boscis and oesophagus are— (1) There is an abundant radial mus- 

 culature in the wall of the proboscis. (2) The longitudinal 

 muscle fibres are arranged less compactly in the proboscis than 

 in the oesophagus. (3) The lining epithelium of the proboscis is 

 less definitely developed than in the case of the oesophagus. 



The crop is a thin-walled sac extending backwards from the 

 oesophagus as far as the fiftieth 

 annulus. It lies close to the 

 dorsal body-wall owing to the 

 enormously developed ventral 

 median lacuna in this region. 

 It gives origin to six pairs of 

 diverticula, as is the case in 

 Glossiphonia heteroclita. In 

 the young individuals found 

 attached to the adult and 

 evidently about to become 

 free, only five such diverticula 

 are present, the sixth pair 

 being developed later anterior 

 to these five. This last-deve- 

 loped pair of diverticula is 

 quite permanent in character, 

 and not merely due to a tem- 

 porary dilatation of the crop, 

 as is found to be the case in 

 some species. Each caecum is 

 connected with the crop by a 

 slender passage in the adult, 



[t-sc 6 



Fig. 3 — Glossiphonia australiensis, sp.n. 



but 



youn 



2 individuals no 



well marked 



passage can be discerned, as distinct 



* Fig. 3. — Glossiphonia australiensis, sp.n. Young individual showing the 

 digestive system, and the position of the six pairs of testes. 



pr.s., proboscis sac— pr., proboscis— te., testis — crop sc. 1, second pair of 

 crop cseca of adult — vl., valve between crop and stomach — crop sc. 6, last 

 pair of crop caeca— st. dv., stomach diverticulum — re, rectum. 



