150 BULLETIN OF THE MUSEUM OF COMPAKATIVE ZOOLOGY. 



Fig. 14. An older larva from the body of parent. Abactinal view. The club-shaped 

 bodies ad^ are spines of the second pair of adambulacrals, which in this 

 stage project beyond the periphery of the disk. 



PLATE III. 



Fig. 15. View of the calcareous plates of the actinal side of the disk of Amphiura in 



a pentagonal larva younger than PL II. Fig. 13. 

 " 16. One fifth of the actinal hemisome of an older pentagonal larva than last. 



This figure has, in addition to plates of Fig. 15, the ventrals v, and orals o. 

 " 17. Pentagonal larva, actinal view, older than last, showing the origin of the 



lateral plates Ip. 

 " 18. Abactinal view of an older larva in which the arms have increased in length, 



the terminal plate being pushed outward by the formation of the lateral 



and ventral plates. One arm is shaded, two adjacent arms drawn in 



outline, and two arms not represented. 

 " 19. The arm and portion of the abactinal hemisome of an older Amphiura. 



Three pairs of lateral arm-plates are represented, and two dorsals are 



shown. Abactinal view. 

 " 20. An arm and portion of the actinal hemisome of a larva about the same age 



or slightly older than the last. 



