Astasiaea.] THE infusoria. 153 



121. Astasia flavicans. The yelloiv Astasia. — Body- 

 extensible, cone-shaped, approaching cyhndrical, and 

 rounded at the foremost extremity. Tail very short and 

 blunt ; ovaria of a yellowish colour. Found in yellow- 

 ditch water. Length about 1 -430th. 



122. Astasia pusilla. The dwarf Astasia. — Body 

 extensible, cone-shaped, swelling out, and rounded at the 

 foremost extremity ; tail very short and pointed, colour- 

 less. Group 69 represents two of them magnified. 



Ehrenberg remarks, they are often so abundant, that 

 thousands, perhaps millions, of these creatures are some- 

 times contained in the hollow of a watch-glass^ and that 

 they rise up and form a stratum on the surface of the 

 water. They might have been mistaken for the young of 

 the A. flavicans, but that the vesicles within them, which 

 appeared to be digestive cells, were larger than those in 

 that species, which is also without proboscis. As soon as 

 a little colouring matter was thrown into the water, an 

 evident current was observed near the fore part of the 

 creature; and by this means, in 1833, the thread-like pro- 

 boscis, which is about half the length of the body, was first 

 perceived. Sometimes the entire creature appeared to 

 glisten. Should this species, upon closer inspection, be 

 found to be ciliated, it would be rightly placed in Peri- 

 dinea. Length 1-1 440th to 1 -840th. 



123. Astasia (?) viridis. The green Astasia. — Body 

 extensible, and of an ovato-oblong form, distended a little 

 at the middle ; tail very short and pointed ; green. Found 

 amongst conferva. Length 1-1 200th to 1 -900th. 



124. Astasia nivalis. The snoiv Astasia. — Form oval, 

 extremities rounded, rarely pear-shaped, colour deep 



