PLATE V. 



Fig. 26. — Horizontal section through a larva somewhat older than that, of tig. 24, but younger than that of fig. 25. 

 Shows the separation of the cells of the nephridia] pit into two wings. ,',- Oil Immersion. X 8 Oc. 

 Camera. X 704. 

 Fig. 27. — Horizontal section of posterior end showing slightly older stage in the development of the nephridia than 



that of fig. 26. j 5 . Oil Immersion. X 8 Oc. Camera. X 704. 

 Fig. 28. — Horizontal section through a larva with beginnings of two tentacles. Shows nephridia. ,' 2 Oil Immersion. 



X 8 Oc. Camera. X 704. 

 Fig. 29a. — Transverse section through posterior end of a larva with two pairs of tentacles. T W Oil Immersion. X 8 



Oc. Camera. X 704. 

 Fig. 29b. — Continuation of series 29a. Taken through the region of the rectum. t l . Oil Immersion. X 8 Oc. 



Camera. X 704. 

 Fig. 29c. — Continuation of series 29«. Taken through the middle of the larva. T *.v Oil Immersion. X8 Oc. 



Camera. X 704. 

 Fig. 29c. — Continuation of series 29a. Taken through the hotly proper and the lower part of the hood. T K Oil 



Immersion. X 8 Oc. Camera. X 704. 

 Fig. 29r/. — Continuation of series 29n. Taken through body and hood near the region of the mouth. ^ Oil 



Immersion. X 8 Oc. Camera. X 704. 

 Fig. 30. — Almost a sagittal section through a larva with two tentacles. r l 2 Oil Immersion. X 8 Oc. Camera. X 704. 

 Fig. 31. — Larva with three pairs of tentacles. Outline drawing from life. 1 Ob. < 4 Oc Camera. X 225. 

 Fie. 32. — Larva with five pairs of tentacles. Outline drawing from life. | Ob. < S Oc. Camera. X 202. 

 Fig. 33. — Larva with six pairs of tentacles. Outline drawing from life. s Ob. X 8 Oc. Camera. X 202. 

 124 



