FOSSIL ASTERIADZA. 301 
The body of the animal was inclosed in a crustaceous 
case formed of large plates, articulated to each other by 
suture; the mouth or oral aperture was situated in the centre 
of the plated integumental cover of the receptacle. The 
organs of locomotion and prehension consisted of five arms 
or brachial appendages, formed of ossicula as in the crinoidea, 
and the whole was invested with soft tissue or integuments. 
When floating in the water, the creature could spread out 
its tentacula, and form a net to capture its prey, and by 
closing them, secure it, and convey it to its mouth. The 
figure, Lign. 96, is restored from specimens which separately 
exhibit the parts here represented in connexion. 
ooo 
Fossiz ASTERIADA. 
The radiated animals, popularly called Star-jfishes, from 
their stellular forms, are so abundant on our coasts, that the 
common five-rayed species must be familiar to all my readers 
who indulge in rambles on the sea-shore, and will serve as 
an illustration of the general appearance and structure of 
the beings whose petrified remains now claim our attention. 
This species belongs to the division of Asteriadee, in which the 
rays are elongated, and far exceed in length the diameter of 
the disk; in another group (Goniastea, or Cushion-star), the 
body is angular, and the lobes or rays are short, and not 
longer than the diameter ; while in a third subdivision (Coma- 
tula and Ophiura), the arms are distinct from the body, and 
articulated, elongated, and ramified, as in the Crinoidea, 
The external surface of the common Star-fish is soft, and 
attached to a tough coriaceous integument, investing a skele- 
ton composed of an infinite number of calcareous ossicula, 
arranged in regular series along the margins of the rays. 
Each ray has a longitudinal furrow, perforated at the sides 
by alternating rows of pores, through which tubular tenta- 
