TIMA. 



61 



fact, all are gelatinous, all are more or less transparent, and it is 

 not easy to describe the various shades of solidity in jelly. Per- 

 haps they may be more accurately represented by the impression 

 made upon the touch than upon the sight. If, for instance, you 

 place your hand upon a Zygodactyla, you feel that you have 

 come in contact with a substance that has a positive consistency ; 

 but if you dip your finger into a bowl where a Tima is swimming, 

 and touch its disk, you will feel no difference between it and the 



Fig. 76. 



Fig. 77 



water in which it floats, and will not be aware that you have 

 reached it till the animal shrinks away from the contact. 



The adult Tima, represented in Fig. 76, is not more than an 

 inch and a half or two inches in diameter. Instead of count- 

 less tubes diverging from the digestive cavity to the margin of 

 the disk, as in the Zygodactyla, there are but four. The di- 

 gestive cavity in the Tima is much smaller than in the Zygo- 

 dactyla, and is placed at the end of the proboscis, which is long, 

 and hangs down far below the disk. This removal of the diges- 

 tive cavity to the extremity of the proboscis gives to the tubes 



Fig. 76. Tima; half natural size. 



Fig. 77. One of the lips of the mouth at the extremity of the long proboscis ; m mouth, d digestive 

 cavity, c chymiferous tube. 



