294 
Holothuria floridana and Holoihuria atra 
B. Characters Common to the Two Species. 
Dimensions. — In both adult and young the standard deviation is least in the 
diameter, greater in the length and greatest in the volume. The relatively much 
larger standard deviation in the volume of the adult when compared with that of 
the young is to be expected because of the limited range of the latter. 
Dist7-ibution of pedicels and papillae. — In both adult and young the standard 
deviation in the distribution of these appendages is considerably greater in the 
trivium. 
I'entacles. — Mode, 20. As shown by the average standard deviation of "7 in 
adult and young of H. floridana and of "9 in H. atra the number of tentacles show 
but little variation when compared with most of the other characters. 
The greater tendency in variation to less than the normal number, probably 
comes from the loss of tentacles by accident rather than from inherent congenital 
variation. It is therefore likely that the majority of the small and medium sized 
tentacles are stages in regeneration. 
Variation in the location of the tentacles lying in the dorsal inter-radius with 
reference to the mesentery attachment is shown in about 20 7o of the specimens. 
The tentacular ampullae have branches only in the adult and hence the 
formation of such branches, when it occurs, comes with advancing age. 
Pedicels and papillae defined. — The typical pedicel is cylindrical, with sucker, 
end-plate of Type A or B, sometimes with supporting rods different from those of 
the papilla. 
The typical papilla is conical, without sucker, with end-plate of Type D or E 
and with supporting rods of its own kind. 
The typical pedicels and papillae are connected by a group of appendages not 
definitely cylindrical or conical, with suckers either present, rudimentary or absent, 
having end-plates of Type G and with supporting rods either present or absent. 
End-plates. — Standard deviation much the largest in Type A, decreasing 
relatively less and less with each succeeding type. 
Supporting rods: — in papillae and tentacles; straight or curved rib-like rods 
with ends spinose, branched, or expanded, and with 1 to several holes. 
In pedicels. — Straight, or slightly curved, rods with a hole in each expanded 
end. Sometimes with branched ends and several holes. Connecting links to the 
perforated plates of the body-wall may be found towards the base of the pedicel. 
Tables. — The table developes from a short rod with forked ends. These ends 
divide and the recurved branches from either end grow together and fuse, forming 
the 4 larger primary holes of the centre of the disc. Then 4 smaller secondary, 
and often still smaller tertiary, peripheral holes are formed as the disc is com- 
pleted. At the same time the vertical rods arise and then are bound together 
