264 
Holotliuria floridana 
The rosettes are specially abundant and thus characterize specimens 18, 26, 42, 
47, 52, 53, 71, 75, 78, 80—86, 93, 95, 106, 113—118, twenty-five in all, of which 
eighteen, or 72°/^, are young as judged by the criterion of size (cf. pp. 239, 243). 
But of the other seven, four do not much exceed the limit for the young (50 c.c.) 
and the remaining three are considerably below 209 '58 c.c, the average size of the 
adult. Allowing for a natural variation in which some young are larger than the 
limit I have assumed, it may be asserted that, for the most part, the rosettes are 
characteristic of young specimens. The perforated plates characterize 25 specimens, 
15, 19, 21—25, 36—38, 51, 54, 55, 57—67, 72, all of which are adult. So without 
question the perforated plates are characteristic of the adult. Four fully grown 
specimens 32, 50, 56, 69, have 90 perforated plates and 10 developmental 
stages, thus closely approaching the adult state. Holothurid 17, with 90°/^ de- 
velopmental stages and 10°/^ perforated plates, and 30, 31, 33, with 90°/^ develop- 
mental stages and 10 rosettes, present such intermediate conditions as would 
be expected in occasional individuals. Specimens 44, 76, 79, 94, have 90 7o 
rosettes and 10°/^ developmental stages, thus mostly presenting a young condition. 
Of these four, 44, an adult, has a volume much less than the adult average, while 
the other three are young but above the average for the young. In view of these 
facts it is clear that the large majoritij of spicules in the young are rosettes and in 
the adult, perforated plates, while a number of specimens give the intermediate 
stages of the developmental series. Some rosettes and developmental stages may 
be found in any adult and some perforated plates in any young. 
Mitsukuri, 1897, discovered that, in Sticliopus japonicus Selenka, with ad- 
vancing age the tables gradually degenerate " until in full-grown individuals, 
there are found nothing but small perforated plates, representing only a small 
central part of the basal disc and without any trace of the spire." In H. floridana 
I have found correlated with advancing age a succession in the developmental 
stages of the perforated plate, but not a series of degenerative changes in the tables. 
H. Calcareous Spicules of the Ambulacral Appendages and the 
DiflTerentiation of Pedicels and Papillae. 
The differentiation of pedicels and papillae is of primary importance. An exact 
definition of each of these two classes of ambulacral appendages is much needed. 
In such definitions the elements to be especially considered are {a) Form, 
(6) Suckers, (c) End-plates, and {d) Supporting Rods, together with the correlation 
of these elements. The end-plates and supporting rods are additional to the 
tables, rosettes and perforated plates described above for the body-wall, and found 
as well in the walls of the pedicels and papillae which are evaginations of the 
body-wall. 
From 9 holothurids 88 dorsal ambulacral appendages were taken, and from 3 
other specimens, 50 ventral appendages. In a number of cases certain elements 
were not sufficiently clearly seen for accurate judgment and so are called "not 
determinable." 
