PLATE I. 



Fios. 1, 2, 5, 7, 9. — Awplnporiis midlihantdliis. 

 ,, 3, 8. — Prostomn unU'inratum. 



„ 4, 6. — Baseodiscus imtarcticiis. 



Fk;. 1. — Amjihipunis iiiiillilutftafiis, Jouhiu. Doi'sal view of anterior end, showing E., tlie two groups 

 of eyes. 



Fk;. 2. — Amjihipoms mvltihastatus. Ventral view of anterior end. M., single opening of the mouth and 

 proboscis-pore ; C.S., cephalic slits. 



Fic. 3. — Prostoma unilineatum (Joubin). Dorsal view of the entire animal, x 8. Pr., the partially 

 everted proboscis. 



Fk;. 4. — Baseodiscus antdrciicus, sp. n. Ventral view of anterior end, showing G., lateral grooves in 

 which the openings of the cerebral organs are situated : M., mouth ; P.P., proboscis-pore. 



Fic. 5. — Atuphiporus multihastatus. Transverse section near the anterior end. B.M., basement-mem- 

 brane ; Ciec, anterior c.Bcum of the intestine ; CM., circular muscle-layer ; D., a genital 

 duct ; Ep., external epithelium ; G., gonadial sac (testis) ; L.M., longitudinal muscle-layer ; 

 L.N., lateral nerve-stem ; L.P., lateral pouch of intestinal caecum ; Pr., proboscis ; P.S., cavity 

 of proboscis-sheath ; Pyl., pyloric canal. 



Fif:. 6. — Baseodiscus antarcticus. Transverse section at about the middle of the body. B.M'., primary 

 basement-membrane ; B.M^., secondary basement-membrane ; CM., circular muscle-layer ; 

 Ep., external epithelium ; Gl., glandular layer of the integument ; Int., intestine ; L.M'., inner 

 longitudinal muscle-layer ; L.M^., outer longitudinal muscle-layer ; L.N., lateral nerve-stem ; 

 Pr., proboscis ; P.S., cavity of proboscis-sheath. 



Fiii. 7. — Amphiporus nudtihiistatiis. Middle portion of the proboscis, seen by transparency, showing the 

 armature and reserve-stylets. 



Fk;. 8. — Prostoma unilineatum. Transverse section in the middle region of the body. Ep., external 

 epithelium : Int., intestine ; L.N., lateral nerve-stem ; Ov., ova ; Pi., dorsal band of pigment ; 

 P.S., cavity of proboscis-sheath. 



Fk;. U. — Amphiporus multihastatus, ? . Transverse section in the middle region. B.M., basement- 

 membrane ; CM., circular muscle-layer ; G., gonadial sacs, containing ova ; Int., intestine ; 

 L.M., longitudinal muscle-layer; L.N., lateral nerve-stems; P.S., cavity of proboscis-sheath. 



