12 (//) A caudal sensory organ present (Fig. 20); no asexual reproduction. 



.Genus Hesiolicium. 



@ 



y^^iC> 





-ip~^ < f^' 



haptocilia 



Figure 20. — Hesiolicium inops. 



12 (//) Caudal sensory organ absent (Figs. 21, 22); both sexual and asexual reproduction 



Genus Paratomella. 



(TOO, 0^ o<\,0' r cv" 



Figure 21. — Paratomella unichaela. 



Figure 22.— Paratomella rubra, sagittal section through body at level of male accessor) organs. 



13 (5) Mouthopeningat or close to the anterior end of body 14 



13 (5) Mouth opening not close to anterior end 18 



1 4 (/i) Male pore close to mouth at anterior end; bursa seminalis absent 

 14 {13) Male pore not close to mouth; bursa seminalis present .... 



Family HOFSTENIIDAE' (p. 61) 15 



Family HALLANGllDAE (p. 60) 17 



'The Hofsteniidae are sometimes placed in an order or suborder separate from the Acoela (e.g.. Karling 1940). However, until this point has been resolved by further studies, the tendency at pre- 

 sent appears to be to retain them in the Acoela (see Steinbock l%6, for a complete review of this question). 



14 



