THE AXLMAL LIFE OF THE GROUP. 489 



to connect with the l)ull:)-like sacks i" that in turn connect with the tube-feet. 

 Sea water is forced into this system of tubes and by the expansion or contrac- 

 tion of the little sacks, the feet are thus extended or withdrawn. 



The favorite food of the starfishes is said to consist of tlie conunon bivalves, 

 but it is asserted that there is no animal tliat it can catch that it Avill not 

 devour. On the oyster beds, especially along the Atlantic coast, they are very 

 destructive. They wrap themselves about the oyster and in so doing literally 

 turn the stomach inside out through the mouth. In a little while the bivalve is 

 forced to relax its muscles and allow the shell to open. The edge of the 

 stomach is then inserted between the valves of the shell and the soft parts of 

 its prey are thus digested outside the starfish's body. The habits of our Ha- 

 waiian species have not as yet been studied, though it w-ould not be a difficult 

 matter to do so. 



Large specimens of an eight-rayed starfish i'' are occasionally captured at 

 Pearl Harbor. They are often a foot and a half in diameter, are cream-colored 

 above, mottled with burnt sienna and chocolate, and are white below. A 

 similar but very small species is to be found abundantly in the coarse green 

 sponges in Kalihi bay and at Pearl Harbor. A small, stiff, irregularly-de- 

 veloped pink leather-like species,^^ without spines, is occasionally found 

 crowded into small holes in the coral reef. It is remarkable for its powers of 

 reproducing new and complete animals from the broken fragments of the old 

 one ; a single specimen in the laboratory has been made to produce a dozen or 

 more complete animals from the fragments broken from the parent, while the 

 parent disk has gone on and reproduced all the lost parts. 



A curious five-sided form, ten inches or more in diameter, has also been 

 taken in the shallow water in Pearl Harbor, but of recent years the dredging 

 operations have apparently driven the large species away. My friend Dr. 

 Walter K. Fisher was on the great Albati-oss expedition and has described 

 fifty-two of the sixty species taken on that cruise as new to science. They are 

 placed in twenty families and are distributed into no fewer than forty-six genera. 

 As can be imagined, the collection represents a most astonishing variety of 

 starfish forms. But as the collection was made in water from ten to a thou- 

 sand fathoms down, his splendidly-illustrated monograph is an index to what 

 is in the great deep offshore, rather than a guide to the forms liable to be 

 gathered by hand by the wading naturalist. 



The Brittle-Staefish. 



The brittle-stars 1'' have long serpent-like arms attached to a relatively 

 small and usually rounded disk-shaped body. They diflfer from the ti'ue stars 

 in a number of ways. It is important to note that the digestive system does 

 not extend into the arms, but is confined in the central body, and that they 

 have no grooves on the under side of the arms, such as exist in the typical star- 

 fish. The arms are long and very fiexible and are used almost entirely as the 

 organs of locomotion. 



