Tricladenstiidien. I. 



373 



»Xous TaTons troiive sur des Fucus resicidosus et des Ulva 

 intestinalis. « 



Durch das breit herzförmige Vorderende und die ziemlich scharf 

 ausgesprochene halsartige Einschnürung hinter demselben unterscheidet 

 sich PL littoralis leicht von andern marinen Tricladen. 



Planana (?) macrostoma Darwin ^ 1844. [? Cercyra macrostoma 



Hallez2 1892.] 



Ich gebe aus Darwixs Beschreibung nur die für die Identi- 

 fizierung wesentlichen Stellen wieder: 



»External alimentary orifice situated in the posterior half of 

 body: mouth-sucker nearly subcylindrical, bell shaped, yery long. - . . 

 »Its base is united, in the middle of the body. to the three principal 

 branches of the intestinal cavity; the two posterior branches unite 

 and form a ring, enclosing the space in whieh the mouth sucker and 

 its external orifice are situated. The three main branches receiye 

 the moss-like subdivision of the intestinal cayity, which reach all round 

 nearlj to the margin of the body. The main, medial, intestinal cayity 

 ends at tbe anterior extremity in a small. opake, wedge-formed mass; 

 ou each side of which, nearly on the dorsal surface, a black ocellus 

 is sitiiated. Between the lateral branches on each side of the medial 

 cavity, seyen or eight internal spherical cayities lie, including opake 

 balls, which I presume are immature oya ; the anterior ones were 

 most developed: they were not present in the smaller specimens. or 

 in all the full-grown ones. I was unable to discoyer any genital 

 orifice. though no doubt one or two exist: near the posterior ex- 

 tremity there was a colourless space. but I could not see any orifice. 

 Anterior extremity square, truncate. with the edges thin and pre- 

 hensile; the animal attaches itself by this part, almost licke a leech 

 with its sucker, and thus drags its body: posterior extremity broadly 

 rounded. Aboye, faintly coloured brownish purple in Striae, with a 

 colourless space over the alimentary orifice. Length 0.2 ths 5 mm); 

 breadth 0,06 ths (0,13 mm) of an inch. ; 



Chonos Archipel, Westküste yon Südamerika; in Brackwasser, 

 unter Steinen, Daravix. 



Epithel. 



Die einschichtige Körperdecke der untersuchten marinen Tricla- 

 den wird, wenn wir yon Bd. Candida absehen, yollständig oder doch 

 1 DAIl^^^x. 18. S. 247. Hallez. ;32. S. 128. 



