512 F. W. GAMBLE. 



behind, tapering slightly in front. The extreme anterior 

 margin truncate. Tentacles more conspicuous in adults than 

 in young specimens, where they form mere blunt marginal 

 projections. Immature specimens derive their coloration 

 from the white or yellowish-white ground-tint and from 

 the branches of the intestine, which, owing to the trans- 

 parency 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 ten- 

 tacle 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. XXXIX, 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 be- 

 tween tide- marks (Mcintosh 45) ; Falmouth, at low water 

 (W. Garstang) ; Plymouth, in 4^ fms., along with young 

 specimens j Port Erin, Isle of Man, in 12 fms. (F. W. G.). 



Distribution. — Naples (Lang). 



This species, closely similar to young smooth specimens of 



