MOLLUSCOIDEA — BRYOZOA 



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in the fossil state. Fossil Bryozoa are known from the Lower 

 Ordovician to the present. 



Derivation of name. — Bryozoa > Greek bryon, moss, + 

 zoon, animal. The colonies frequently look like tufts of moss. 



Bryozoa are subdivided into the following sub-classes and 

 orders : — 



1. Ectoprocta 



a. Gymnolaemata 



b. Phylactolaemata 



2. Endoprocta 



Sub-class i, Ectoprocta 



Colonial Bryozoa with the mouth inside but the anus out- 

 side the tenacle-bearing lophophore (whence the name from 

 Greek ektos, outside, -{- proktos, the anus). A well-developed 

 introvert is present. 



Order a, GymjtolcBmata 



Almost exclusively marine ; lophophore circular ; epistome 

 absent (whence the name from Greek gymnos, naked, + laimoSy 

 the gullet) . At present the marine forms live from tide level to a 

 depth of over 18,000 feet. Geologically they extend from the 

 Lower Ordovician to the present. All fossil Bryozoa known, 

 with possibly a single exception, belong here. 



Fig. 70. — The marine bryozoon, Membranipora. A, M. pilosa (X 15) from the 

 coast of Massachusetts. Portion of a colony seen from above. B, single cell of 

 same seen in profile. C, same with one of the individual animals expanded as in 

 feeding. D, a fossil species, M. rimulata Ulrich ( X 10), from the Eocene of 

 Maryland. (From Ulrich. A-C from Verrill and Smith.) 



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