BRITISH MARINE TURBELLARIA. 195 



8. Microstoma grcenlandicum, Levinsen (51). 



Length 1*75 mm. Body composed of about eight zooids, in colour 

 resembling M. lineare. Eyes absent. Ciliated grooves small. Rhabdites 

 well developed anteriority, more sparsely behind. No sexual organs 

 were observed. 



Habitat. — Among Ulva, Plymouth Sound (F. W. G.) ; Millport 

 (v. Graff). 



Distribution. — Egedesminde, Greenland (Levinsen). 



I place the Plymouth specimen here, for although it does not agree 

 exactly with Levinsen's original description (the red spot at the anterior 

 end is wanting), it does agree with a form described by v. Graff from 

 Millport, and placed under this species. 



Genus 6. — Alaurina, Busch (26). 

 Hermaphrodite Microstomidce, with tactile anterior " proboscis." Usually 

 ivith posterior setae, ; paired lateral ones sometimes present. 



9. Alaurina claparedii, v. Graff. 



Length '3 mm. Anterior end modified to form a tactile proboscis 

 provided with numerous circular folds. The base of the proboscis is 

 marked off by a tuft of cilia on each side. A single posterior group 

 of setse at the hinder end. The posterior sixth of the body is marked 

 off transversely (probably an indication of fission). 



Habitat. — Coast of Skye (Claparede). 



Claparede (35) described this form as a rhabdoccele larva, but it 

 was referred to Alaurina by Metschnikoff (37). It is probable that 

 this genus is not uncommon on our coasts. 



Family MESOSTOMIDiE. 



Rhabdocoela with one or two genital apertures ; yolk-glands and germaria 

 distinct or united. Testes compact. Female accessory organs present. 

 Pharynx ventral, rosidate (for the term " rosulate " see v. Graff, 

 'Monogr./p. 80). 



