402 ECHINODERMATA. ECHINJDES. 



ginal lobes, more or less numerous, radiating, and moveable ; 

 no anus. 



The Stellerides, including the genus Astcrias of Linnaeus, are so named from their 

 body being radiated or divided into arms around a common centre, with the mouth 

 below, which serves also as the anus. The skeleton of the body is composed of 

 small osseous pieces variously combined ; and the reproductive power is such, that 

 not only is one ray or arm when taken away speedily reproduced, but even a single 

 ray is sometimes found to originate others, and to form a complete animal. In the 

 genus Asterias each arm has a longitudinal furrow below, full of small holes, through 

 which the feet or filamentous processes are extruded. The rest of the under surface 

 is furnished with small moveable spines. All the surface is also supplied with 

 tubes much smaller than the feet, which appear to absorb the water and pass it into 

 the general cavity for the purpose of respiration. In the middle of the body, a 

 little to one side, is a small stony plate, of which the use is not known. In the in- 

 terior, and immediately over the mouth, is a large stomach, from which originate two 

 ccecums for each ray," ramified like a tree, and suspended each in a kind of mesen- 

 tery. There are also two ovaries in each ray ; and it appears that the Asterias are 

 hermaphrodite. The bony skeleton consists principally for each division of a sort of 

 column composed of stony circles, from which arise cartilaginous branches which 

 support the exterior envelope. Other bony parts, to which are often attached move- 

 able spines, accompany the lateral margins of the arms. Lamarck divides the Stel- 

 lerides into four genera. 



Gen. 16. ASTERIAS, Lam. Lin. 



Body suborbicular, depressed, divided in its circumference into 

 angles, lobes, or rays, disposed in a stellated form ; under 

 surface of tbe rays furnished with a longitudinal furrow, bor- 

 dered on each side with moveable spines, and holes for the 

 tubular or retractile feet ; mouth inferior and central, at the 

 union of the furrows. 



This genus of animals is popularly known by the name of Sea-stars. They are very 

 common on most coasts. The upper surface is generally coloured. It is red in some, 

 violet or blue in others, orange, yellow, reddish, or a mixture of these. The infe- 

 rior surface is commonly whitish yellow. Their skin is coriaceous, more or less gra- 

 nular or tubercular, and moveable in all directions. The inferior surface, as above 

 remarked, presents as many longitudinal furrows as there are arms or rays'. These 

 rays, diverging from the mouth, which is their centre of union, end at the extremity 

 of the arms. Along the margins of the furrows are many rows of short, slender, 

 and moveable spines, which are often so numerous that Reaumur counted upwards 

 of fifteen hundred in a ray. Besides these spines, the Asterias are provided with 

 very numerous small holes along the margin of the furrow, or perforations for the 

 passage of retractile tubes, which serve to fix the animal to marine bodies, or for lo- 

 comotion ; and still smaller tubes on the dorsal surface, for the purpose of respira- 

 tion. The mouth, situate below and in the centre, is armed with five bony proces- 

 ses, which meet and shut the centre of the opening. This aperture serves also as 

 the anus. The Asterias feed on marine worms, Crustacea, and small shell-fish. 

 Lamarck divides the genus into 1. Those in which the angles, lobes, or rays, do 

 not exceed in length the diameter of the disc. 2. Those in which the rays are elon- 

 gated, and much exceed the diameter of the disc. 



* Rays shorter than the central disc. 



A. tesselata, Lam. Body flattened, pentagonal, tesselated, subgra- 

 nular ; margin articulated. Inhabits seas of Europe, America, 

 and India. Lam. ii. 552. 



A. reticulala, Lin. Five lobed, large, thick; back reticulated, rough 

 with short spines, irregularly inflated in the centre ; lobes coni- 

 cal and spinous, or dentated. 10 to 12 inches broad. Inhabits 

 Indian seas Lam. ii. 557- 



