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 sanely 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 Jatan 



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 



