SAND-STARS AND STAR-FISHES, 193 
reach. It is variable in color, but beautifully spotted with 
ale and brown, its general hue being a brick-red. _Agn- 
hiura squamata Sars has long slender arms and is 
vhite ; it lives below tide-marks. The basket-fish, me- 
usa’s head, or Astrophyton 
{gassizit Stm., is of large 
ize, the disk being two in- 
hes across, and the arms 
ubdividing into a great 
umber of  tendril-like 
ranches. It lives from ten 
9 one hundred fathoms in 
ae Gulf of Maine. 
Ophiurans are widely dis- 
tributed, and live at depths ” 
etween low-water mark and = *é mel? 
vo thousand fathoms. Fos- _rig.135—ophiopholis bellis, common Sand 
1 Ophiurans do not occur "After Morse. 
1 formations older than the Upper Silurian, where they are 
*presented by the genera Protaster, Paleodiscus, Acroura, 
ad Lucladia ; genuine forms closely like those now living 
gpear in the muschelkalk beds of Europe (Middle Trias). 
Order 2. Asteridea.—In the true star-fishes the arms are 
irect prolongations of the disk, and the stomach and 
‘ig. 1386. ~Three forms of Star-fish, A, B, C, seen from above, showing the different 
veropment of the ambulacral and intcrambulacral areas. The ambulacra are indi- 
ed by rows of dots; 0, mouth; 7, urms; ér, interradial or interambulacral areas. 
Pleruster; B, Goniodiscus; A, Asteriscus.—After Gegenbaur. 
‘aries or spermaries project into them, and there is a deep 
abulacral furrow, while the interambulacral spaces vary 
uch in development (Fig. 136); the feet are provided with 
