BRITISH MARINE TURBELLARIA. 443 



the body. Their most characteristic form is that of a U, the 

 curved portion beinpj much thicker than the long slender 

 processes. 



The mouth is almost mid-ventral. It leads into a funnel- 

 shaped pharynx. Two genital apertures are present. 

 The male pore lies a short distance in front of the hinder end, 

 the female pore still further forward. The conical penis 

 encloses a vesicula seminalis in its proximal part. The 

 ovaries extend throughout the greater part of the body. A 

 spermotheca, possessing intrinsic and extrinsic muscles, 

 opens into the vagina. The epithelium of its duct (according 

 to V. GraflF) secretes a cuticle. 



Habitat. — Among stones and seaweed at the base of the 

 littoral zone, Plymouth, Port Erin, Isle of Man (F. W. G.) ; 

 Millport (v. Graff). 



Distribution. — Naples, Trieste, Roscoff (v. Graff) ; Den- 

 mark (Oersted, 21) ; in colonies among Laminaria and Fucus, 

 a few feet below the surface, Bergen (Jensen). 



4. Aphanostoma elegans, Jensen. 



Length '75 mm. Body colourless, with a lobate dark 

 green spot in the centre due to coloured parenchymatous 

 vacuoles. Form broadly rounded in front, tapering gently 

 posteriorly. Eyes absent. The male genital aperture lies 

 a short distance in front of the hinder end; the female pore 

 close behind the green spot. According to Jensen the sper- 

 matozoa are long, filiform, thicker and spirally twisted 

 anteriorly. 



Habitat. — Among Ulva, between tide-marks, Plymouth 

 (F. W. G.). 



Distribution. — Alvcerstrom and Bergen (Jensen, 49). 



Jensen's description reads, " Corpus utraque extremitate 

 rotundatum in anteriore parte latius, retrorsum sensira an- 



