Plate VIII. 



Fige. 122, 123. — Two sagittal sections through a larva of the 15 p. c. stage. 



x 210. cr n . a pair of cirri added ventrally. 

 Figs. 124-127. — Transverse sections through a larva of the 15 p. c. stage. 



x 210. n. Anlage of the " Hauptarmnerv." n. pd. nervus pedun- 



cularis. er", pair of cirri added ventral!}'. 

 Fig. 128. — Arm-apparatus and body proper of a larva of the 15 p.c. stage, 



(ventral view), from an unstained but clarified preparation, x 210. 



Circles on occ. pst. " Haftzellen " of the occulusor posterior. 

 Fig. 129. — Small portion of the body cavity with the blood corpuscles 



and spindle bodies (sp. bd.) from the same preparation as that 



drawn in Fig. 128. x 380. 

 Fig. 130. — Longitudinal section through the shell of a larva of the 10 



p. c. stage, x 500. pr. ost. periostracum. 

 Fig. 131. — Marginal part of the mantle of a larva of the 12 p. c. stage, 



from life, x 180. r. m. radial muscle. 

 Fig. 132. — Portion of a seta from a stained preparation of a larva of the 



12 p. c. stage, x 500. 

 Fig. 133. — Eight portion of a transverse section through a larva of the 



15 p. c. stage, x 490. 

 Fig. 134. — Left portion of transverse section through a larva of the 15 



p. c. stage, x 490. /«*. ventral lip or the funnel forming part 



of the ileo-parietal band. 

 Fig. 135. —Portion of a sagittal section passing through the opening of 



the nephridium of a larva of the 15 p. c. stage, x 532 (immers). 

 Fig. 13G. — Transverse section through the peduncle of a larva of the 15 



p. c. stage, from the same series as Figs. 124-127. The left figure 



is nearer the posterior end of the peduncle, x 210. 

 Fig. 137. — Longitudinal section through the end of the peduncle of a larva 



of the 15 p. c. stage, x 700. 

 Fig. 138. — Portion of a sagittal section through a larva of the 15 p. c. 



stage, showing the section of the arm-apparatus, x 490. 



