242 ZOOLOGY 
of these are provided with glands which open to the exterior 
near the tip of the jaws; the glands are said to secrete a sticky 
fluid by means of which the Echinoid attaches to itself pieces 
of seaweed, etc., which screen it from observation. The smaller 
Fic. 144.—Pedicellariae of Kchinus saxatilis. 
After Gegenbaur. 
a. Open. 6, Closed, 
pedicellariae serve chiefly to clean the surface of the body, and 
some of them serve as locomotor organs, and to catch passing 
worms, etc. They are well supplied with nerves, and some of 
them have in addition a special tactile organ. 
The peristomial area immediately surrounding the mouth 
Fic. 145.—View of Sea Urchin, with part of the shell removed to show the course 
of the alimentary canal (from Leuckart). After Cuvier. 4 
1. Mouth, surrounded by five teeth (dis- 5. The siphon. 
placed). 6. Oral vascular ring. 
. Lantern of Aristotle. 7. Aboral sinus. 
. Oesophagus, coiled intestine, and 8. Blood-vessel accompanying intestine. 
rectum. 9, Ampullae at base of tube-feet. 
4, Ovaries with oviducts. 
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