Development of Holothiiria Floridana Pourtales 223 



canal in the fourth day (PL I, Figs. 4-5, pvp). After hatching 

 in the sixth day, this pedicel develops a sucker, and by the eighth 

 day it exceeds the tentacles in length. On the seventh day, the bud 

 of the second pedicel evaginates from the mid-ventral radial canal 

 to the left. On the ninth day this pedicel appears externally (PI. II, 

 Pig. 7, b). On the twenty-second day the third mid-ventral pedicel 

 arises between the first and second, and on the thirty-third day, the 

 fourth, behind the third (PL II, Fig. 8, c, d). On the fortieth day, 

 the fifth mid-ventral pedicel appears behind the fourth (PL II, Fig. 

 10, e). After the primary posterior mid-ventral pedicel, the next 

 four develop to the left from the mid-ventral radial canal. It is not 

 until the fortieth day that the bud of a pedicel appears to the right 

 from the mid-ventral radial canal (PL II, Fig. 10, MVrp). The 

 ventral pedicels are thus inaugurated in an asymmetry beginning 

 with development to the left of the mid-ventral radial canal. In one 

 lot of embryos of which I have now only sketches from life, the 

 development was more rapid than given above, since a specimen of 

 the fourteenth day has three, and one of the nineteenth day, four, 

 left mid-ventral pedicels. 



In Table II, the appendages of the young of my alcoholic series, 

 from four to eighty-seven days old, are seriated with reference to 

 their place of origin. In the stages later than nine days, variation 

 in the number of appendages will be noted in the individuals. In 

 part, this is to be associated with accelerated or retarded growth, 

 and in part, with natural variation. As noted above in connection 

 with the tentacles, at least in one lot of embryos, individuals devel- 

 oped more precociously. 



On the twenty-fourth day, the buds of the first pair of papillae 

 appear ventrad from the anterior parts of the dorsal radial canals, 

 inaugurating the bilateral symmetry later shown, in a general way, 

 in the distribution of the appendages. By the thirtieth day these 

 buds have developed, and by the thirty-third day the buds of five 

 more dorsal papillae have appeared (PL II, Fig. 9). From the first, 

 these papillae are especially developed and prominent (Pis. II-III, 

 Figs. 9, 10, 12, 14; rdpa 1, 2, 3, Idpa 1, 2, 3). Later the ventral 

 series of the dorsal papillae become the lateral warts so characteristic 



