FRESH-WATER POLYZOA. 229 



4. In adherent, pendent stems formed of urn - shaped 



cells (d). 



a. Jelly mass rounded, adherent, often very large. 

 Pectinatella, 1. 



a. Jelly mass long, narrow, slowly travelling. Cris- 



tatella, 2. 

 ft. Lophophore horse-shoe shaped. Plumatella, 3. 



b. Lophophore circular. Fredericella, 4. 



c. Lophophore circular, tentacles in a single row. 



Paludicella, 5. 



d. Lophophore circular or oval, tentacles in a single 



row. Urnatella, 6. 



1. PECTINATELLA MAGNIFICA (Figs. 155, 155a). 



The appearance to the naked eye of the colorless 

 jelly-like substance siwroimding the bodies, and of the 

 animals themselves, has already been referred to. 



Pectinatella is not sensitive to sound, but a jar or 

 shock to the water sends the an- 

 imals into their contracted state 

 very suddenly. The colonies are 

 numerous throughout the summer 

 and until October. They are most 

 frequently found in the shade, al- 

 though they may live in the sun if 

 below the water. Exposure to air F i g . isspectinattiia mag- 

 and sunlight together is speedily 

 fatal. Therefore transfer the jelly to the collecting- 

 bottle as soon as possible, otherwise you will have, on 



