THE LARVA OF ASTERIAS VULGARIS. 127 



PLATE XIV. 



Fig. 13. — Showing mauner of formation of the ciliated baud by the disap- 

 pearance of the general ciliation. The dotted portions represent the ciliated 

 areas. Living specimen, x 240. 



Tig. IL — Larva four days old, seen from the right side, showing the right 

 water-tube and pore. Kleinenberg's picric salt; Delafeld's hsematoxylin 

 preparation, x 145. 



Fig. 15. — Longitudinal section through the apex of the preoral lobe, to 

 show the ectodermal thickening, ap. From a specimen of about the same 

 age as Fig. 11. Perenyi ; Kleinenberg's hsematoxylin preparation, x 600. 



Fig. 16. — Section showing mode of formation of the water-pore and pore 

 canal. Similar conditions were observed in the living specimens. Perenyi ; 

 Kleinenberg's hsematoxylin preparation. X 600. 



Fig. 17. — Larva of five days, seen in ventral view to further show the 

 history of the relation of the adoral band to the preoral portion of the circum- 

 oral band, and the formation of the oral depression. Kleinenberg's picric 

 salt ; Delafeld's hsematoxylin preparation, x 70. 



Fig. 18. — Diagram of a reconstruction from serial transverse sections, to 

 show the form and position of the left enterocoel soon after its union in the 

 preoral lobe with the right enterocoel. As seen from the left side. x. The 

 point where the constriction will appear which divides the left enterocoel into 

 an anterior and a posterior. 



Fig. 19. — Longitudinal section, parallel with the dorsal and ventral sur- 

 faces, of a larva in same stage as Fig. 14, but just after the closure of the 

 right water-pore. The pore canal persists, but in the sections following the 

 one here figured it is found to end blindly. Perenyi j Kleinenberg's hsematoxy- 

 lin preparation, x 240. 



Fig. 20. — Larva of six days, at the stage when the division of the circum- 

 oral band takes place (see Figs. 25 and 26), showing the dorsal surface. Only 

 the left water-pore is now present. Kleinenberg's picric salt ; Delafeld's 

 hsematoxylin preparation. X 70. 



Fig. 21. — A longitudinal section, parallel with the dorsal surface, through the 

 two water-pores. The part of the section through the preoral lobe is not 

 here figured, though it is in Fig. 22. x 350. 



Fig. 22. — The second section, ventralwards from that shown in Fig. 21, 

 It shows the bilaterally symmetrical water-tubes, which in Fig. 21 are seen to 

 open on the dorsal surface, x 350. 



Fig. 23. — From the living animal, four days old, showing the dorsal mesen- 

 chymatous muscle-fibres which move the preoral lobe. It also shows the 

 bilaterally symmetrical water-pores. X 145. 



