136 MR. H. CHARLTON BASTIAN'S MONOGRAPH 



Hab. Amongst half-tide sand and stony debris very abundant, and also found once 

 on a bright grass-green filiform weed (free from Diatomaceae) from tide-pool, Falmouth. 



2. O. GLABER, n. sp. (Plate XI. figs. 129, 130.) 

 Female, length -^", breadth era "• 



External Characters. — Body tapering slightly forwards, but considerably towards 

 posterior extremity, which is long, narrow, and pointed, and terminates with a minute 

 sucker. Head rounded, naked. Integument plain or with longitudinal markings. 



Pharyngeal cavity y^ee " long. (Esophagus about :jth of total length, embraced ob- 

 liquely, near its middle, by an (esophageal ring. Intestine thinly covered with hepatic 

 particles. Anus xko" from posterior extremity. Vulva about middle of body. Excre- 

 tory ventral duct 



Male, not seen. 



Mab. Marine surface-mud from estuary, Falmouth. 



3. O. viscosus, n. sp. (Plate XI. figs. 131-133.) 

 Female, length -j^", breadth yy? "• 



External Characters. — Body long and filiform, scai^cely at all narrowed anteriorly, 

 but tapering gradually to a point at posterior extremity, which terminates with a minute 

 sucker. Head bluntly rounded, provided with a circlet of four setae. Integument 

 plain or with longitudinal markings, having numerous fine particles of sand and diatoms 

 adhering to its external surface. 



Pharyngeal cavity txit" long. (Esophagus yth of total length, embraced obliquely, 

 near its middle, by an oesophageal ring. Intestine sparsely covered with hepatic par- 

 ticles. Anus -2^-2" from posterior extremity. Vulva at middle of body. Uterus 

 bifid. 



Male, the same length as female, breadth -g-sj"' 



Anus 2^" from posterior extremity. Spicules solitary, of an elongated wedge-shaped 

 form, and two" long. 



Sab. Marine surface-mud from estuary, Falmouth. 



When a thin layer of mud is spread out with water on a slip of glass, I have met 

 with this species generally floating on the surface, appearing under a hand-lens as a 

 slowly moving pellucid filament. 



4. O. Fuscus, n. sp. (Plate XI. figs. 139, 140.) 

 Male, length \" , breadth 



166 



External Characters. — Body stout, of a brownish colour, tapering slightly forwards, 

 but abruptly posterior to anus. Terminal sucker minute. Head narrow, rounded, 

 having a circlet of 6-8 short, thick setai at ttso" from anterior extremity. Integument 

 having longitudinal markings ; slightly tinged of a blackish colour at posterior ex- 

 tremity. 



Pharyngeal cavity -^^' long, large, elongated-oval; one tooth much larger than 

 either of the other two. (Esophagus about ^th of total length ; slightly enlarged pos- 

 teriorly ; no ring visible. Intestine thickly covered with dark-brown hepatic particles ; 

 tessellation indistinct. Anus j^" from posterior extremity. Spicules long and narrow. 



