TURBELLARIA 



159 





no vasa deferentia or oviducts being present. The subclass contains 2 



families and about 40 species, of which 6 have been found in America. 



Key to the families of Acocla: 



fli One genital pore present 1. Propobidae 



Oj Two genital pores present 2, Convolutidae 



Family 1. PEOPORIDAE. 



But one genital pore present; position of mouth various: 5 genera 

 and 14 species. 



1. Childia von Graft". Mouth in ventral surface behind the middle; 

 pharynx absent ; bursa semi- 

 nalis absent; 2 male copu- 

 latory organs, each with a 

 chitinous stilet : 1 species. 



C. spinosa v. Gr. (Fig. 

 253). Length 1.4 mm.; 

 color light yellow: Woods 

 Hole. 



2. Anaperus von Gr. 

 Body elongate; bursa sem- 

 inalis and pharynx absent : 

 1 species. 



A. gardineri v. Gr. 

 (Fig. 254). Length up to 

 6 mm. ; width 1 mm. ; color 

 red, but yellow at the two 

 ends: Woods Hole, with 

 PolycJiaerus caw^a^ws^ which 

 it resembles, but is much 

 less numerous than it; 

 movements rapid. 



Family 2. CONVOLUTIDAE. 



Two genital pores present, the female pore being in front of the 

 male; bursa seminalis present; mouth near the middle of the body: 5 

 genera and 25 species. 



1. Aphanostoma CErsted. Body cylindrical or flattened beneath 

 and narrowed behind; mouth near the middle; statocyst present; eyes 

 absent: 2 species. 



A. diversicolor CErst. (Fig. 255). Body very variable in shape, 

 elliptical, with yellow at forward end; middle usually violet; length 

 1 mm. ; width .25 mm. : Newport, R. I., and Woods Hole, among algae in 

 shallow water, common; Europe. 



Fig. 254 



Fig. 253 — Childia spinosa (von Graff). 1, stato- 

 cyst ; 2, ovary ; 3, mouth ; 4, penis ; 5, genital pore. 

 Fig. 254 — Anaperus gardineri (von Graff). 1, stato- 

 cyst ; 2, mouth ; 3, ovary ; 4, genital pore. 



