248 



AQlTATIC MICROSCOPY FOR BEGINNERS. 



must, of course, be in a horizontal position. The 

 mirror may then be swung above the stage, and 

 PlumaUUa viewed by reflected light as an opaque ob- 

 ject It is exquisitely 

 beautiful in this position, 

 as is Pectinatella or any 

 of the Polyzoa; but the 

 animals are very timid. 

 To see the expanded ten- 

 tacles will therefore de- 

 mand much tiwie and 

 patience. 



Plumatella is almost 

 as common as Pectina- 

 tella. A board or a log 

 that has been floating 

 undisturbed in the pond 

 will, during the summer, 

 be almost sure to afford a rich harvest of Plumatella 

 if its under surface be examined. 



The statoblast of Plumatella is shoWn in Fig. 174. 



5. FREDERlCfiLLA.. 



The colonies of this Polyzoon are found in the 

 shadiest places and near the shores of shallow ponds, 

 growing like Plumatella, and' often in company with it, 

 on the lower surfaces of floating or submerged objects. 

 The whole colony may be adherent, or only the base, 

 the stem and branches then floating. A single animal 

 inhabits each hollow branch, and resembles Plumatella 

 in appearance and in structure. It may be distin- 

 guished from Plumatella, however, by the oval or 

 nearly circular lophophore, that of Plumatella being 



Fig. 170. — Plumatella; colony and 

 expanded lophophore. 



