552 THE WHITE SAXD-tiTAR. 



body from which it can hardly be expelled, the ambulacra, or feet, are seen to put themselves 

 in motion, some being thrust out while others are being withdrawn. 



OUR next examples are very curious species of Star-fish. 



The BKITTLE-STARS (Ophiocoma rosulcC), of which there are several species, are very appro- 

 priately named, inasmuch as they are able to break up their rays in the most extraordinary 

 manner, a capability which they mostly exercise when they feel alarmed. The generic name, 

 .Ophiocoma, is derived from two Greek words, the former signifying a serpent and the latter 

 a lock of hair. 



The whole of the Brittle-stars are curious and restless beings. They can never remain in 

 the same attitude for the tenth part of a second, but are continually twining their long arms, 

 as if they were indeed the serpents with which Medusa's head was surrounded. The least 

 impurity in the water will cause these strange beings to break themselves to pieces in this 

 extraordinary manner, but they never seem to disintegrate themselves with such rapidity as 

 when they are touched, or otherwise alarmed. 



The lamented Professor Forbes has left an admirably quaint description of this suicidal 

 process. Having in vain attempted to secure a perfect specimen of a Brittle-star, he thought 

 that he might achieve that object by having a pail of fresh water lowered into the sea, so that 

 as soon as the dredge reached the surface of the sea it might be transferred to the bucket of 

 fresh water, and all the inmates killed at once by the shock. 



A fine specimen of the genus Luidia was then taken in the dredge. "As it does not 

 generally break up before it is raised above the surface of the sea, cautiously and anxiously I 

 sank my bucket to a level with the dredge's mouth, and proceeded, in the most gentle manner, 

 to introduce Luidia to the purer element. Whether the cold element was too much for him, 

 or the sight of the bucket too terrific, I know not ; but in a moment he began to dissolve his 

 corporation, and at every mesh of the dredge his fragments were seen escaping. In despair, I 

 grasped the largest, and brought up the extremity of an arm with its terminating eye, the 

 spinous eyelid of which opened and closed with something exceedingly like a wink of derision." 



These Brittle-stars are, however, extremely capricious in their exercise of this curious 

 power. It sometimes happens that, as in the instance so amusingly narrated, the creatures 

 break themselves to pieces without any apparent provocation, while, in other cases, specimen 

 after specimen may be taken, handled, killed, or wounded, without the loss of a ray. Even 

 in the aquarium, they are eqiially uncertain in their habits, at one hour being entire and 

 splendid specimens, and at the next being little but a solitary disc amid a ruined heap of 

 broken arms. 



The Brittle-stars are abundant in the warmer waters. When Dr. Gould published his 

 " Report on Invertebrata of Massachusetts," 1841, his enumeration of Echinodermata embraced 

 Echinus granulatus, Sea-egg, Sea-urchin ; Asterias, four species. A. rubens being the common 

 Star-fish, or Five-finger ; and two species of Ophiura, which were visible only as brought up 

 by dredging, or from the stomachs of fishes. The latter were not, as they are in the tropical 

 waters, found crawling on the objects at low tide or in shallow waters. The coral shrubs, and 

 dead and crumbling blocks of Meandrinas astreas, etc., are numerously inhabited by them. 

 There are many others since discovered by the extensive dredging in deep and shallow waters 

 on our coast. 



THE WHITE SAND-STAR (Ophiurus albidus). 



The word Ophiurus is of Greek origin, signifying snake-tail, and is therefore very appro- 

 priately given to these curious beings, whose slender arms twist and coil just like a handful of 

 small serpents. 



The Ophiuri are quite as voracious as the ordinary Star-fishes, and are able by means of 

 the long arms to convey food to the mouth, which is placed in the central disc. The young of 

 these Echinodermata are quite as curious as those of the sea-urchins, to which, indeed, they 

 bear some resemblance. They have long been known to naturalists under the title of Easel 

 animalcules, on account of their peculiar shape, their real origin not being suspected until later 



