Plate XXX. 



Figs. G?) (o-e). — Are taken from several parts of serial sagittal sections of 

 /i-type larva of 28 tentacles. 



a. median section through the hood and the collar, x 2 D. 

 h. more magnified fignre of the nerve ganglion (g/.) and the 

 jmsterior recess of the preoral cavity (p.r.) in the preceding fignre. 

 X 2 F. 

 c. taken from a section lateral to the œsophagns and to the right 



of that of the fignre a. x 2 F, 

 (I. ventral portion of tlie collar-trunk walls, where the septum (mes.) 



and the adult collar cavity (s.c.c.) are cut through, x 2 F. 

 e. portion of a section which passes through the second tentacle 

 (t"). X 2 F. 

 Figs. G4 («-/"). — Transverse sections taken from serial sections of a meta- 

 morphosing larva of type A represented in fig. 11. The respective 

 explanations of them are introduced in the text (p. 584). From 

 a to c magnified as x 2 D, and from d to /' as x 2 F. 

 Fig. Cj. — Portion (right side) of a transverse section throug'n the tentacular 

 region of a metamorphosing larva of type A, slightly younger than 

 that of fig. 11. X 2F. 

 Fig. CG. — Transverse section through the nephridial region of wholly meta- 

 morphosed larva of type A. x 2 F. 



