84 NATURAL SCIENCE [August 
individuals there are found nothing but the small plates above- 
mentioned. These represent a small part of the original table top, 
and are comparatively thinly scattered in the skin. 
In the youngest stages the calcareous deposits are the most com- 
plete, and have almost the character of a coat of armour, like that of 
a star-fish or sea-urchin. This may be for the greater protection of 
the young, in which the skin and muscle-layers are very thin and 
pliable; but it may signify the descent of the species from a more 
richly plated ancestor. These differences are not entirely signs of 
age, but, in conjunction with others, distinguish geographical races. 
Thus forms with spicules in the shape of buttons are more common 
in the north of Japan, and are also characterised by numerous long- 
pointed papillae set in four rows along the back and sides, with 
many smaller papillae between them. As one passes southwards 
along the coast one comes gradually to forms that have only a row 
of low papillae along the sides, and a few scattered over the back. 
Habitat, however, has its influence no less than latitude. Those 
that live among rocks have a larger number of tall papillae, and are 
of a mottled brown colour, while those that live on sandy ground, 
probably among sea-weeds, have lower and fewer papillae, and are of 
a dark-green colour, 
This interesting and doubly important paper makes one doubt 
afresh the validity of the many species of holothurians that have 
been based on the examination of the spicules of a few individuals; 
it shows the necessity for the examination of many specimens in 
various stages of growth from different localities; and it affords one 
more demonstration of the value of the study of all growth-changes 
and not merely of those that occur in the embryo. 
How A BRITTLE-STAR LIVES IN JAPAN 
WHILE the Japanese zoologists, K. Mitsukuri and T. Hara, were on 
a collecting tour last year, they came, on April 1, to a sandy shoal 
in the Bay of Kagoshima. Wading into the water, they were soon 
struck by very curious objects. “ Numerous slender stalks a few 
millimeters in diameter and 10-15 centimeters high were standing 
up from the bottom, looking like the stems of so many weeds. 
Along one side of each stalk there was, however, a row of white 
papillae-like structures. These stalks were mostly by twos, although 
sometimes only one was standing by itself. We do not remember 
having seen three making a group. As we dug, to learn more about 
these curious objects, we were greatly surprised to find that they 
were the arms of ophiurans, and that the papilla-like structures were, 
therefore, no doubt, tubefeet. So far as we could see there was no 
difference between the five arms of the animal, and why only one or 
