218 APPENDIX. 



neath this, is the same portion enlarged. "When 

 magnified to this apparent size, the cells could be 

 seen in different states, some closed, and others with 

 their bodies protruded. When magnified to 3 d, we 

 could pleasantly watch the gradual eversion of the 

 membrane, then the points of the tentacles slowly 

 appearing, and then, when fully protruded, suddenly 

 expanding into a bell-shaped circle. This was their 

 usual appearance, but sometimes they could be noticed 

 bending inwards, as in fig. 3 c, as if to imprison some 

 living atom of importance. Fig. h represents two 

 tentacles, showing the direction in which the cilia 

 vibrate. 



Ceisia denticulata. Fl. I. fig. 4. 



I have only drawn the cells from a prepared speci- 

 men. Tlie polypes are like those described above. 



Gemellaeia loeicata. Fl. I. fig. 5. 



Here the cells are placed in pairs, back to back. 

 5 a is a very small portion on the natural scale. 



