BRITISH MARINE TURBKLLARIA. 495 



1857-8. FoviA AFFiNis, Stimpson (32a). 

 1865. Planaria affinis, Johnston (38). 

 1878. FoviA AFFINIS, Jensen (49). 



Length 4 — 6*5 mm. Body linear-oblong, convex above, 

 flat beneath. The form of the anterior end is described by 

 Johnston and figured by Dalyell as slightly enlarged and 

 rounded. Oersted's (16) pi. i, fig. 6, probably represents this 

 species. The explanation of the plate states it to be Planaria 

 littoralis, which, however, is not the case, since the latter is 

 synonymous with Planaria ulvse. A specimen taken at Ply- 

 mouth is figured on PI. XXXIX, fig. 9. The anterior end 

 tapers slightly, and when viewed "end on " presents two slight 

 lobes, which are used in a vigorous sensitive way, as in the 

 case of Convoluta paradoxa. 



The colour varies from greenish-brown to wood-brown. An 

 oval white spot in the hinder half of the body marks the 

 pharynx. The two eyes lie each at the inner side of a white 

 area, and from them a pair of dark parallel streaks of pigment 

 run to the anterior margin. 



The movements of the animal are very striking. The 

 most usual method of locomotion is by arching the body and 

 drawing the hinder end up to the anterior one. These 

 " geometer " or leech-like movements are repeated with great 

 rapidity. This kind of motion is chiefly efi'ected on moist 

 surfaces. When, however, the water is deeper, the usual 

 gliding ciliary movement is adopted. The hinder part of the 

 body is kept on the substratum, while the anterior extremity 

 is raised up and constantly extended and retracted, the body 

 as a whole partaking of the steady forward movement.^ 



Habitat.— Among algae. Firth of Forth (Dalyell); Plymouth 

 (F.W.G.). 



Distribution. — Coasts of Denmark, Norway, and Sweden. 



* Bergendal ("Studien ii. nordischen Turbellarien," ' Ofvers af Kongl. 

 Vetensk-Akad. Forhandiingar,' 1890, No. 6) has described a species 

 apparently synonymous with the present one, in which the uterus has a 

 separate external opening. He defines a new genus, Uteriporus, containing 

 the single species U. vulgaris, Berg. Au accident prevented a re-examina- 

 tion of my specimen. 



