160 



PLATHELMINTHES 



2. POLYCH<ERTJS Mark. Body broad and flat with either one or sev- 

 eral caudal filaments: 1 species. 



P. caudatus Mark (Fig. 256). 

 Body with parallel sides and a deep 

 notch in the hinder margin, from which 

 1 to 3 caudal filaments arise; color red; 

 length 4 mm. ; width 1.5 mm. : on stones 

 along the beach from Casco Bay to 

 Long Island Sound; often abundant; 

 movements sluggish. 



SUBCLASS 2. CCELATA. 



Turbellarians with intestine: 3 

 orders. 



Key to the orders of Ccdata : 



! Small forms with a straight intes- 

 tine 1. RHABDOCOZLIDA 



a 2 Usually larger forms with branched 



intestine. 

 &! Intestine with 3 main branches. 



2. TBICLADIDA 

 & 2 Intestine with many large branches. 



3. POLTCLADIDA 



Fig. 255 Fig. 256 



Fig. 255 ApJianostoma diversicolor 

 (von Graff). 1, statocyst ; 2, female 

 genital pore; 3, bursa seminalis; 4, 

 male genital pore. Fig. 256 Poly- 

 chosrus caudatus (Mark). 1, testis; 

 2, mouth ; 3, ovary ; 4, female genital 

 pore ; 5, male genital pore. 



ORDER 1. RHABDOCCELIDA. (FiG. 257.) 



Marine, fresh-water, and land turbellarians of small 

 size in which the intestine is a straight and unbranched 

 or at the most only slightly lobed tube or sac; yolk 

 glands present or not; either 1 or 2 genital pores pres- 

 ent: 23 families, grouped in 2 suborders with over 350 

 species, of which about 75 have been found in this 

 country; about half the species marine. 



Key to the suborders of Rhabdoccelida: 



Oi Intestine a straight tube 1. RHABDOCCELA 



o a Intestine sac-shaped with irregular sides. .2. ALIXEOCOZLA 



Fig. 257 Dia- 

 gram cf a rhab- 

 doccelid (Dalyel- 

 lia) (von Graff). 

 1, mouth; 2, 

 brain ; 3, intes- 

 tine; 4, yolk 



SUBORDER 1. RHABDOCGELA.* 



Body cylindrical, fusiform, filiform, or lamellate in 

 shape; intestine a tube or sac, usually with straight 

 sides; usually 2 eyes and occasionally sense pits and gland .A te ~ s ^J|: 

 statocysts present; either a single median or a pair of 7 ovary, 

 excretory canals present; many forms reproduce asexually, by terminal 

 budding: 16 families and 275 species, 48 American. 



* See "Monographic d. Turbellarien, I. Rhabdoccelida," by L. von Graff, 1882, 



