126 ANIMALS 



(d) A proglottis cleared and mounted may show the reproductive 

 organs, viz: ovary, shell gland, vitelline glands, uterus, testes 

 and genital pore. 



103. Aschelminthes: 



(a) Note the form and movements of a living "vinegar eel" or a 

 thread worm from an aquarium. 



(b) In Ascaris note the form of the body, the terminal mouth with 

 its lips, and the anus. If the body is slit open the intestine and 

 reproductive organs may be identified. 



104. Annelida: Study a living leech 'in water. Note its method of swim- 

 ming, and locomotion by means of its suckers. 



105. Echinodermata: 



(a) In an aboral view of a starfish (Asterias) note the type of 

 symmetry, the central disc and the arms or rays. On the 

 general surface will be found the hard spines and soft papulae; 

 on the disc the madreporic plate. 



(b) If a living specimen can be had study it in sea water for the 

 method of progression. 



(c) On the oral surface are the mouth, the ambulacral grooves 

 with the ambulacral feet, the radial nerve ridge in the middle 

 of each ray and, at the tip of each arm, a tentacle and eye spot. 



(d) If the aboral wall is removed the stomach and hepatic caeca 

 * come into view and beneath these the gonads and the ampullae 



of the ambulacral system. Note also the structure of the skel- 

 etal system. 



(e) Compare a sea-urchin with a starfish. 



(f) Compare a sea-cucumber with a starfish. 



106. Arthropoda: 



(a) Compare a crab with the crawfish. 



(b) Observe some living fresh water Entomostraca with the micro- 

 scope. 



(c) Study a "thousand-leg" or centipede. 



(d) Study a spider. 



(e) For further studies on insects consult a work on entomology. 



107. Mollusca: 



(a) Study the method of locomotion of a common snail. Note 

 symmetry of body and shell. 



(b) In a right lateral view note the head, the foot, the collar 

 and shell. Note also the mouth, the tentacles, the eyes, the 

 respiratory opening. 



