THE TURBELLARIA 



Sub-Order 3. Acoela. 



Fam. 1. Proporidae. 

 2. Aphanostomidae. 



Order 2. Tricladida. 



Fam. 1. Otoplanidae. 



2. Procerotidae. 



,, 3. Bdelluridae. 



, 4. Planariidae. 



5. Leimacopsidae. 



,, 6. Geoplanidae. 



,, 7. Bipaliidae. 



,, 8. Cotyloplanidae. 



9. Rhynchodemidae. 



Order 3. Polycladida. 



Fam. 1. Planoceridae. 

 2. Leptoplanidae. 

 3. Polypostiidae. 

 4. Cestoplanidae. 

 5. Anonymidae. 

 6. Pseudoceridae. 

 ,, 7. Euryleptidae. 

 8. Enantiidae. 

 9. Prosthiostomidae. 



10. Diplopharyngeatidae. 



The Turbellaria are Platyhelmia, with a ciliated epidermis, in 

 which the body is nearly always flattened, oval, or leaf- shaped. 

 In the epidermis special cells occur, which may give rise either to 

 mucus, or to granular rod-like bodies, or to definite "rhabdites," 

 which are discharged from the body on irritation. 



Historical. The name " Planaria " was given by 0. F. Miiller 

 in 1776 to certain worms living in fresh and salt water, and 

 characterised by a leaf-like form, which had previously been 

 confused with a Fluke and a Tapeworm under Linnaeus's name 

 " Fasciola " ; later, Miiller's genus Planaria (which included some 

 Nemertines) was split up into numerous genera, and the genus 

 Planaria restricted to certain fresh-water forms ; but it has also 

 been employed by several authorities as the name of the class. 

 The name "Turbellaria" was invented by Ehrenberg in 1831 to 

 include not only " Planarians," but also the elongated Nemertine 

 worms, which, by means of cilia borne by the epidermis, produce 

 the well-known movement of small particles coming within their 

 reach, giving rise to the appearance of a whirlpool. 



Cuvier (1817) was the first to separate his genus Nemertes 

 (representing the Nemertines) from Planaria, and formed the 



