Plate XXVII. 



Fig. 32. — Traiisver«e section through the luiddle portion of a larva in wliicli 



the ventral groove has ceased to give olï" niesoblast cells, x 2 F, 



with the tube drawn out. 

 Fig. 33. Slightly oblique sagittal section of a larva in which the nc[)hridial 



pit {ne p.p.) has made its tirst appearance, x 2 imni. '/,^. 

 Fig. 34. — Oblique frontal section of a larva nearly at the same stage as in 



Fig. 9. X 2 F. 

 Fig. 35. — Transverse section through the nephridial pouch {nep.j).) as yet un- 

 paired. X 2 F. 

 Fig. 36. — Oblique sagittal section of the nephridial pouch (iwp.p.) partly 



divided, x 2 F. 

 Fig. 37 and Fig. 38. — Show respectively sagittal and frontal sections of 



larva?, in which the proximal end of the nephridial pit is about 



to divide into two. x 2 F. 

 Figs. 39 («-c). — Three transverse sections of the two nejihridial canals, each 



of which has respectively an internal 0[)eniiig. x 2 F. 

 Fig. 40. — Sagittal section of a larva at the stage represented in Fig. 10. 



X 2 F. 

 Fig. 41. — Frontal section of a larva at the same stage as the })receding, in 



which the two nephridial [>ores have separated widely from eacii 



other. X 2 F. 

 Fig. 42. — Oblique frontal section through the nephridial region of a larva a 



little younger than the preceding, x 2 F. 

 Fig. 43. — Transverse section through the U[)[)er portion of the ieso[ihagus of 



a larva of four tentacles, x 2 F. 

 Fig. 44. — Large mesoblast cells which are Ibund in the bod}'-cavity of the 



larva of two or four tentacles, x 2 F. 



{All ifie figures from fig. 45 to fig. 0^ arc drawn from larvœ 



of liipc A.) 



Fig. 45. — Median sagittal section of a larva of 12 tentacles, x 2 D. 

 Fig. 46. — Portion of a longitudinal section of a larval tentacle of 10- 



armed larva ; two blood cor[)Uscles are re[)resented in the tentacular 



cavity (vorp.). x 2 F. 



Figs. 47 (a-c). — Three longitudinal sections of the ncjihridium nt a larva of 



J 2 tentacles, x 2 F. 



Fig. 48. — ]\lodian frontal feclion of a larvu uf 16 tentacles, x 2D. 



