MORPHOLOGY OF OTOCYSTS OF GONIONEMUS. 2Q5 



With reference to the tentacles these organs display no abso- 

 lutely fixed relationship. Though they usually alternate with the 

 tentacles they may occur in pairs between two adjacent tentacles 

 or two or more tentacles in continuous sequence may have no 

 intervening otocyst. 



In G. vertens, nos. 6 and 7 had three paired otocysts between 

 adjacent tentacles ; no. 7 also had two abnormal otocysts with two 



TEXT FIGURE 3. Abnormal otocyst with two sensory spheroids within the 

 same primary vesicle. 



sensory spheroids in each capsule Text Figure 3. Hargitt (1901 : 

 249) has noted this last mentioned variation and has called 

 attention to its relative infrequence. Specimen no. I of G. mur~ 

 bachii had thirteen paired otocysts and no. 2 of the same species 

 had eight. 



SUMMARY. 



1. There are two distinct vesicles in the otocyst of Gonloncnius. 



2. It seems probable that the conspicuous primary vesicle has 

 chiefly a protective function, enclosing the essential sensory 

 mechanism. 



3. The secondary vesicle contains the otolith within a fluid- 

 filled cavity. 



4. No sensory hairs or ridges have been demonstrated. 



5. Puncture of the primary vesicle as practiced by Murbach and 

 others probably does not impair the essential sensory mechanism. 



6. The otocysts of G. z f crtcns and of G. uiurbachii are in close 

 proximity to the periphery of the ring canal, their capsules im- 

 bedded in the mesoglea so that no portion of them protrudes 

 beyond the margin of the bell. 



7. The number and arrangement of otocysts and tentacles in 

 Gonlonenius is variable. 



