SYNOPTIC KEY 



Class INFUSORIA 



1(2) Cilia present; sucking tubes absent. 



Subclass Ciliata, p. 10 



2(1) Cilia absent in adults; sucking tubes present. (Pratt, 

 67; W. and W., 298.) Subclass Suctatoria 



Subclass CILIATA 



1(4) Cilia usually present on all parts of the body. 2 



2(3) Cilia short, nearly equal in length except in mouth 

 region where they may be longer. (Pratt, 50; W. and 

 W., 271.) Order Holotricha 



3(2) Mouth surrounded by an adoral zone of cilia much 

 longer than those on other parts of the body. (Pratt, 

 57; W. and W., 283.) Order Heterotricha 



4(1) Cilia not present on the whole body surface. 5 



5(6) Cilia absent on the dorsal surface. Cilia of the 

 ventral surface fused to form thickened processes upon 

 which the animal supports itself and moves about. 

 (Pratt, 60; W. and W., 286.) Order Hypotricha 



6(5) A spiral of cilia or membranellae present in mouth 

 region. Other cilia absent save sometimes a girdle of 

 cilia near aboral region. (Pratt, 64; W. and W., 291.) 



Order Peritricha 



Phylum PORIFERA 



1(2) Small, marine, with calcareous spicules. 



Class Calcarea, p. 11 



2(1) Larger sponges, skeleton silicious, horny or absent; 

 never calcareous; some in fresh water. 3 



3(4) Marine. Glass sponges with six-rayed spicules. 

 (Pratt, 77.) Class Hexactinellida 



4(3) Marine or fresh water; skeleton of silicious spicules, 

 spongin, or both or wanting. Class Demospongiae, p. 1 1 



