BRITISH MARINE TURBELLARIA. 249 



branches of the intestine, which, owing to the transparency of the 

 body, are clearly visible. The colour of the gut-branches is scarcely 

 the same in any two specimens, and may be red, orange, brown, black, 

 &c. In mature examples the genital organs conceal the greater part 

 of the alimentary canal. The mouth lies immediately behind the 

 brain. It leads into a cylindrical pharynx, which, lying in its sheath, 

 appears from the dorsal surface as a white oval area. Bounding the 

 sides of this are the first pair of gut-branches, a median branch being 

 absent. In front of the pharynx these two branches unite and from 

 this point a very short median branch runs to the anterior end. Eyes 

 are present below and above the tentacle bases, and also as two 

 divergent series over and slightly beyond the brain. Very characteristic 

 are two pairs of eyes close to the hinder margin of the brain, and a 

 pair on its outer and anterior angles. The relation of these eyes 

 to those of the larva may be gathered from PI. X, fig. 1, which 

 represents a young specimen of the present species. The male genital 

 pore is combined with the mouth behind the brain ; the female pore 

 lies in front of the centre, the sucker just behind it. Granule-gland 

 and vesicula seminalis open into the penis. The vesicula receives the 

 separate vasa deferentia. The uterus encloses the main-gut. A very 

 extensive shell-gland surrounds the female genital pore. 



Habitat. — Firth of Forth (Dalyell, 29) ; not uncommon between 

 tide-marks (Mcintosh 45) ; Falmouth, at low water (W. Garstang) ; 

 Plymouth, in 4| fms., along with young specimens ; Port Erin, Isle of 

 Man, in 12 fms. (F. W. G.). 



Distribution. — Naples (Lang). 



This species, closely similar to young smooth specimens of Cycloporus 

 papillosus, may be distinguished by the absence of a median gut- 

 branch over the white pharyngeal region, by the presence of only 

 5 — 6 pairs of secondary branches (Cycloporus possesses 8 — 9) to the 

 intestine, and by their non-anastomosing character. 



I have included Planaria ellipsis of Dalyell and others under this 

 species, since his figures agree exactly in the points just mentioned. 



III. Summary. 



1. British marine Turbellaria, as at present known, include about 



fifty-seven species of Rhabdoccelida, twelve of Polycladida, and two 



