520 F. W. GAMBLE. 



III. Circular ciliated groove on the head. Oral and 

 genital apertures combined. A pair of germ-yolk- 

 glands present . . Sub-family Cylindrostominae. 



a. With characters of sub-family 



Genus Cylindrostoma. 

 Species: — Cyl. quadrioculatum (pharynx directed 

 forwards; body colourless). Cyl. inerme (epider- 

 mis yellow, containing rhabdites but no " cal- 

 careous bodies;^' spermotheca absent). Cyl, 

 elongatum (pharynx directed backwards ; four 

 eyes present). 



b. Pharynx directed backwards, the penis forwards. 



Spermotheca opens into genital atrium. 



Genus Monoophorum. 

 Species : — M. striatum (pigment carmine, reticular ; 

 muscles grouped in longitudinal bundles). 



8. With two genital apertures, two germaria, and two 

 vitellaria. An otolith present . . . Family Monotidse. 



a. Female genital pore in front of the male 



Genus Monotus. 

 Species: — M. lineatus (an eye present in front of 

 the otolith ; copulatory organ a soft papilla). 

 M. fuscus (copulatory organ a chitinous tube). 

 M. albus (penis, a boat-shaped, chitinous copu- 

 latory organ with a pair of lateral teeth near the 

 "bows"). 



b. Female genital pore behind the male aperture 



Genus Automolos. 

 Species: — A. ophiocephalus (an eye usually present 

 in front of the otolith; head expanded). A. 

 unipunctatus (an eye absent ; penis a spinous 

 tube). A. horridus (head slightly marked oflF from 

 the body ; rhabdites giving a spinous appearance 

 to the animal; penis soft, muscular). 



