TURBELLARIA 169 



Family 2. RHYNCHODEMIDAE. 



Body elongate, with more or less parallel sides; head not distinct, 

 with 2 spherical eyes near the front end; mouth near the middle: 7 

 genera and about 100 species. 



Rhynchodemtjs Leidy. Head end very contractile and often ex- 

 tended like a proboscis; body more or less cylindrical; eyes small: 35 

 species. 



R. sylvaticus Leidy. Body somewhat fusiform, thick, convex above 

 and flattened below, 10 mm. long, 3 mm. thick and 1 mm. wide; forward 

 end narrowed and very extensile; color gray with two longitudinal 

 stripes on the back and a transverse spot near the middle: eastern 

 states, in woody places. 



Order 3. POLYCLADIDA * 



Marine turbellarians, often of large size, with thin, leaf-like body; 

 intestine with very numerous branches which ramify to all parts of the 

 body; eyes numerous; otocysts, tentacles and stiff tactile cilia also often 

 present; no yolk glands; 2 genital pores; mouth central or posterior; no 

 asexual reproduction: 225 species grouped in 2 suborders. 



Key to the suborders of Polycladida: 



Ci No suckers present 1. Acotylea 



Qz A ventral sucker present .2. Cotylea 



Suborder 1. ACOTYLEA. 



Polyclads without a sucker; genital pores near hinder end of body: 



3 families. 



Key to the suborders of Polycladida : 



Qi Two dorsal tentacles present 1. Planoceridae 



a. No tentacles present 2. Leptoplanidae 



Family 1. PLANOCERIDAE. 



Two dorsal tentacles, usually containing ocelli; mouth central; 

 copulatory apparatus directed backwards; marginal and cerebral eyes 

 present or absent : about 8 genera and 45 species. 



1. Planocera Blainville. Body oval or elliptical and flattened; 

 tentacles slender, situated at some distance from front end of body with 

 a cluster of eyes at the base of each; cerebral ocelli inconspicuous; 

 genital pores separate but near together: about 25 species. 



P. nebulosa Girard. Body convex and rather thick, 29 mm. long and 

 10 mm. wide, and usually olive green in color with a median dorsal 

 stripe; mouth central: Charleston to Cape Cod, under stones. 



♦ See "Die Polycladien des Golfes von Neapel," etc., by A. Lang, Fauna a. 

 Flora d. Golfes v. Neapel, xi Monographie, 1884. 



