FIELD BOOK OF PONDS AND STREAMS 



' live for a few days in an aquarium especially if provided with 

 water from their own pond. Bryozoan colonies are beautiful 

 with their nodding lophophores and waving tentacles and the 

 tentacle-wreathed heads of Cristatella look like rose colored 

 fountains. 



Bryozoans cannot be preserved outstretched unless they are 

 put into an anesthetic (p. 41) like chloretone, before the 

 alcohol is poured over them. The branching tubes of Pluma- 

 tella keep well in alcohol ; but the jelly masses of Pectinatella 

 and Cristatella shrink into sorry looking remnants. 



Identification. — Bryozoans are small and their classification 

 is necessarily based upon microscopic structures. Table of 

 the genera of bryozoans described here; modified from Pratt 

 (see Bibliography, p. 413): 



I. Lophophore circular. Order GymnolcBtnata (mouth not 

 covered). 



Family Paludicellidcs 



Colonies delicate and vinelike, on stones and sticks in 

 ponds and slow streams. 



Fig. 104. — Paludicella ehrenhergii: i, colony; 2, 

 branch enlarged. 



Paludicella ehrenhergii. — The colony is partly creeping 

 and partly erect, made up of minute club-shaped animals 

 arranged tandem-wise in the branches (Fig. 104). The 

 statoblasts are oval, ringed with a bluish purple band. Creep- 



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