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, Muller'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 



