ENTEROPNEUSTA HILL. 343 



the branchial region, in the two members of the sub-genus Chlamy- 

 dothorax (P. erythrcea and P. bahamensis) examined by him. 

 Of P. erythrcea he says : " Der Darm (of the part of the genital 

 region immediately following on the branchial region) durch zwei 

 seitlich einspringende Falten in zwei Halbcanale, einen dorsalen 

 und einen ventralen, geschieden erschient. Ersterer stellt eine 

 tiefe Rinne dar, die von einem miichtigen, driisenreichen Epithel 

 ausgekleidet ist ; letzterer dagegen ist breit und niedrig, seine 

 Wand verhaltnissmassig dtinn. Der Querschnitt des Darms ist 

 entsprechend etwa ankerformig."* 



In P. hedleyi this dorsal diverticulum of the gut appears to be 

 more markedly separated from the ventral division than in P. 

 erythrcea, (cf. fig. 11 with Spengel's fig. O, page 182). Tn both 

 cases che dorsal division is lined by a very thick epithelium with 

 numerous glands. 



In P. bahamensis, according to Spengel, the same features 

 are found, but not in such noteworthy proportions as in P. 

 erythrcea. 



In P. flava which, as Willey f has shown, also belongs to the 

 sub-genus Chlamydothorax, I find in the portion of the gut in 

 question a similar subdivision into dorsal and ventral portions. 

 The dorsal division is small and lined by a moderately thick epi- 

 thelium, in which, however, glands are not specially developed. 

 This dorsal division is connected with the large thin-walled 

 ventral division by a laterally compressed stalk, with a very 

 narrow lumen. Gland cells are especially abundant in the thick 

 epithelium of the stalk. Altogether in P. flava this dorsal 

 division of the gut is a much smaller and much less prominent 

 structure than in P. hedleyi. 



Neither in P. hedleyi nor in P. flava is there any differentia- 

 tion of muscular layers in connection with this part of the gut, 

 such as Spengel describes for P. erythrcea and P. bahamensis. 

 In P. hedleyi the above described dorsal diverticulum of the in- 

 testine is such a well defined structure that we cannot but regard 

 it as possessing some definite function. Without doubt it is a 

 mucus-secreting organ, but the presence of granules in the pro- 

 toplasm of its epithelial cells suggests also that it has some 

 other function, probably digestive. In this connection it may be 

 mentioned that in one out of three specimens sectionised, the 

 lumen of the diverticulum contained what appeared to be partially 

 disorganised animal remains. 



* Spengel Loc. tit., p. 182. 



f A. Willey On Ptychodera flava, Esch. Qt. Journ. Micro. Sci., xl., 1, 

 1897, p. 165. 



