80 MANUAL OF ANIMAL BIOLOGY 



are given off which innervate all the interior organs. The 

 innervation of the animal is so complete that the muscle tissue in 

 the walls of every one of the tube feet receives its own tiny 

 branch. It can be shown experimentally that the nerve center 

 which controls all the muscular action is located in the nerve ring, 

 for when it is cut the movements of the animal become erratic and 

 purposeless. 



The locomotion of the Starfish, involving, as it does, the slow 

 expansion and contraction of great numbers of tube feet, is very 

 slow. Very different is this function in the Brittle Star (Ophiura), 

 figured on page 53. The long, flexible arms of Ophiura are 

 supplied with heavy muscles which, under the control of the 

 nervous system, move the arms so as to cause rapid locomotion. 



TEXTBOOK REFERENCES 

 Woodruff, pp. 83-86. 



Curtis and Guthrie, pp. 243-246. 

 Guyer, pp. 79 ; 143 ; 277 ; 676-677. 

 Hegner, pp. 177-198. 

 Newman, pp. 277-289. 

 Shull, p. 86. 



GENERAL REFERENCES 



Coe. Echinoderms of Connecticut (Bulletin 19 of the State Geological and 



Natural History Survey). 

 Crowder. Between the Tides (Dodd, Mead). 



MacBride. " Echinodermata," in the Cambridge Natural ^History (Macmillan). 

 Parker and Haswell. Textbook of Zoology (Macmillan). 



