TURBELLARIA 



165 



SUBORDER 1. PALUDICOLA.* 



Planarians. Triclads with a central mouth, a single genital pore 

 behind it and an elongate, flattened body, which are found in fresh water 

 under stones and on plants, also in wet places under leaves, in mud, etc. ; 

 their food consists of crustaceans, snails, aquatic insects, etc., also of 

 dead animals, and they are themselves preyed upon by fish, insect larvae, 

 etc.; they possess remarkable regenerative powers and certain species 

 (Planaria maculata) are known to multiply by fission; the eggs are laid 

 in cocoons which are attached to stones and plants : 1 family and about 

 100 species, in fresh and often brackish water. 



FAMILY PLANAKIIDAE. 



With the characters of the suborder: about 6 genera. 

 Key to the genera of Planariidae here described : 



Oj But 1 pharynx present. 



6 X Anterior margin rounded or angular. 1. PLANARIA 



6 2 Anterior end truncated 2. DENDROCCELUM 



a 2 Many pharynges present 3. PHAGOCATA 



1. PLANARIA 0. F. Miiller. Body elongate, flattened, 

 rounded or angular forward, usually with a pair of lateral 

 angular projections (auricles), and pointed behind; 2 eyes, 

 each in a colorless area; usually a pair of lateral, elon- 

 gated, and colorless sense spots near the eye: many 

 species, about 9 American. 



P. maculata t Leidy (Fig. 264). Body thin, slightly 

 convex, elongate, tapering to the acute tail, 20 mm. long 

 or less; head end trapezoidal, wider than the body, with 

 an acute median and 2 lateral projections; mouth in 

 hinder half; dorsal surface spotted irregularly with black; 

 ventral surface whitish: North America; the commonest 

 fresh-water planarian. 



Fig. 264 



Planaria 



maculata 



(Woodworth) 



p, pharynx. 



* See "Contributions to the Morphology of the Turbellaria," etc., by W. M. 

 Woodworth, Bull. Mus. Comp. Zool., Vol. 31, p. 1, 1897. "Regeneration in Plana- 

 rians," by T. H. Morgan, Arch. f. Entwickelungsmech., Vol. 10, p. 58. "The Move- 

 ments and Reactions of Fresh Water Planarians," by R. Pearl, Q. J. M. S., Vol. 46, p. 

 509, 1903. "The Reactions of Planarians to Light," by H. E. Walter, Jour. Ex. 

 Zool., Vol. 5, p. 38, 1907. "Die Siisswasserfauna Deutschlands : Tricladida," by 

 L. Bohmig, 1909. 



t See "The Life History and Normal Fission of Planaria maculata," by W. C. 

 Curtis, Proc. Bos. Soc. Nat. Hist., Vol. 30, p. 515, 1902. 



