CHAPTER XIII. 
THE STARFISH AND CLOSELY RELATED ANIMALS. 
The Starfish. The common starfish (Asterias vul¬ 
garis) may be easily found at low tide along the New 
England coast. To obtain the dried specimens for 
study, kill the animal by immersing it in warm fresh 
water. It may then be preserved by hardening it in 
alcohol or in boiling water and drying quickly, or by 
packing in salt. If possible get a living starfish and 
place it in a pail of salt water. 
How does the starfish move ? Observe the ambu- 
lacral feet. 
Do you see the eye-spot at the end of each arm ? 
Where is the madreporic body ? 
Is the animal bilateral ? 
Is each ray bilateral ? 
Are all of the rays of the same size ? How do you 
explain any differences ? 
Are any of the spines movable ? 
Which is the oral and which the aboral surface ? 
With a magnifying glass examine the aboral surface 
for the purpose of finding the minute pincer-like bodies 
called p e dicellar ice. 
Can you find projections of the skin used in breath- 
ing ? 
Examine a dried specimen. 
Are all the spines of the same shape ? 
How many kinds of spines do you find ? 
How many kinds of plates do you find ? 
