23 



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-eu95'«ise«:?->^aei^»xaa*««,.tlie plates are loosely opposed and alloTisr 

 vTater to pass freely between them. In tliis position the gills 

 eire eiucIi longer than during contraction, an.d lie in a:' curve*, 

 figure 3, g, "When the suspensory membranes contract, the longi- 

 tudinal muscles, figure 19, ulm, and 11m, also contract, the gills 

 are shortened, and the plates more closely opposed. 



Sach plate is rendered rather rigid centrally chit-mous 

 rods that are so disposed as to allow flexibility ; and many 

 of the muscle fibers of the plate are attached to these rods in 

 such a way as to insure an even strain and keep the plate from 

 bending ventral ly when pressure is applied. 



E3cperiments were tried to determine, if possible, the 

 part taken by the gills in the collection of food. For this 

 puipose both mutilated and uninjured specimens were used. No 



definite resvilts were reached, but in no case was Kelloa^s obser- 



(7) 



vat ion , that the gills are extremely active food collectors, 



confirmed. Considering the remarkable activity of the palps as 

 collectors of food, such activity for the gills seems rather 

 unnecessary, an.d it would also seem that the p-uinping action of the 

 gills would seriously interfere with their normally performing 

 such a function. 



