Revision of the Holothurioidea. 341 
145 pedicels respectively have a more nearly even distribution from 
both sides of the radial canals of the trivium. Not until specimen 
6, with 180 pedicels, are found the first two pedicels budding into 
the mid-dorsal interradius. In the remaining 4 young holothurids 
there is a steady increase in the total number of pedicels and a 
general tendency to bilateral symmetry and an even distribution 
from the two sides of each radial canal. The pedicels are clearly 
arranged in two rows in each radius and are zigzag from side to 
side. It is only in the earliest stages that one can really speak 
of „single“ rows, and then on the ventral sides of the lateral ventral 
and dorsal radii. 
In the older specimens the pedicels are very retractile. In 
certain cases, near the middle of the body, some pedicels grow 
beyond the two typical primary rows, thus constituting irregular 
partial secondary rows, one to each side of the radial rows. 
In the 10 very young specimens of Table I, the average ratio 
.of pedicels in the dorsal to those in the ventral radii is as 3:5. 
This agrees with LeEvissen, 1886. In the older specimens, 11 and 
12, of Table I, the ratio is 3:6. Hence, with age, the radial series 
of the trivium increase in numbers proportionately more than those 
of the bivium. 
If, including the dorsal interradial pedicels, the total number 
is taken, the ratio of dorsal to ventral increases from 3:5,4 in 
specimen 1, to 3:9 in specimen 6 which has only 2 dorsal inter- 
radial pedicels. As the number of dorsal interradial pedicels is 
augmented (specimens 7—12), the average ratio of dorsal to ventral 
pedicels again becomes 3:5. 
Previous to this paper we have, in addition to Levınsen’s obser- 
vations quoted above, the following brief notes upon the distribution 
of the pedicels in the young. Lürken, 1857, relates that in many 
small examples the feet are almost solely in single radial rows. 
Duncan & SLADEn, 1881, say of a specimen 9 mm. long, that the 2 
dorsal radii have fewer pedicels and these are „in an almost straight 
line, except at the extremities, where the zigzag alternating char- 
acter of the series is clearly manifest“. In an individual of 20 mm. 
the more numerous feet are „in double rows of alternating suckers“. 
Tu£er, 1886, notes that in small individuals the pedicels are radial, 
with only a very few on the dorsal interradius, while in very small 
Specimens the pedicels are only radial. MıcHArLovsk1J), 1904, records 
for his smallest specimen, 17 mm. long, numerous pedicels in the 3 
23* 
