BRITISH MARINE TURBELLARIA. 247 



Length 8 — 11 mm. Breadth 3 — 4 mm. Body delicate, fairly 

 transparent. Form elongate, parallel-sided, broadly rounded behind, 

 produced in front into a pair of long, pointed, contractile tentacles, 

 between which the extreme anterior end projects slightly. Colour 

 white, especially marked along the margins. The mid-dorsal line is 

 brownish or carmine, owing to the underlying main-gut and its median 

 branch. The latter exhibits two conspicuous swellings, one at the 

 point of origin, the other behind the brain. Three to four lateral 

 diverticula arise on each side of the main-gut, and are of a brilliant 

 carmine colour at first, becoming much less conspicuous towards the 

 periphery. The pharynx and genital organs appear as white patches 

 round the main-gut. The mouth is placed in front of the brain. The 

 gut-branches do not anastomose. Eyes are present at the bases of the 

 tentacles, and two sharply defined cephalic groups converge at the 

 anterior end of the brain. The position of the genital apertures has 

 already been mentioned. The male pore lies in front of the female. 



Habitat. — Between tide-marks, Greve d'Azette, Jersey (Kohler); 

 Plymouth Sound, 5—20 fms. (F. W. G.) ; Port Erin, Isle of Man, 

 12—15 fms. (W. J. Beaumont and F. W. G.). 



Distribution. — Island of Lussin, Adriatic (Grube), Naples (Lang). 



After much consideration I have referred several specimens dredged 

 at Plymouth and elsewhere to this species. The distinguishing points 

 are the position of the mouth in front of the brain ; the male genital 

 aperture underneath the anterior end of the pharyngeal sheath ; and 

 the short, sharply defined group of eyes over the brain. 



70. Oligocladub auritus (Claparede). 



1861. Eurylepta AURITA, Clapari.de (35). 

 1884. Oligocladus Auritus, Lang (54). 



Length 18'5 mm. Body oval, transparent, white, the intestine bright 

 reddish-brown. Mouth in front of the brain. Pharynx cylindrical. 

 Main-gut gives rise to three pairs of secondary branches, which do not 

 anastomose. Eyes are present in and round the bases of the tentacles, 

 but, according to Claparede, are absent over tbe brain. The male 

 genital pore occurs just behind the mouth; the female aperture is 

 described by Claparede as almost central. Lang suggests that this 



