Plate 12. 



Fig. 1. Periphyllopsis braueri ; oral view, showing canal system. The walls of the 

 stomach are torn away, leaving only its base with the gastric cirri (ci.g). (c.t) 

 tentacular canal; (c.r) rhopalar canal; (c.l) lappet canal; (go) position of 

 gonad ; (r) rhopalium. Natural size. 



Fig. 2. Atorella vanhoffeni, sp. nov. ; oral view of gonad. X 35. 



Fig. 3. Atorella vanhoffeni. Transverse section of gonad (go), showing that it is a single 

 leaf-like structure attached to the endoderm (en) along one line only, at X. (g) 

 mesogloea. From a photograph, x TO. 



Fig. 4. Atorella vanhoffeni; oral view to ahow canal system; (c.r) rhopalar canal ; (c.t) 

 tentacular canal ; (os) gastric ostium ; (go) gonad ; (r) rhopalium. The adja- 

 cent tentacular and rhopalar canals unite in the marginal lappets. X 14. 



Fig. 5. Nausithoe punctata. Rhopalium showing ocellus (o) and otocyst (oc.) (sc) 

 covering scale. X 125. 



Fig. 6. Nausithoe rubra ; rhopalium. (oc) otocyst ; (sc) covering scale. There is no 

 ocellus. From a photograph, x 60. 



