478 Dritter Abschnitt . Systematik. 



from near its anterior extremity, thu body decreases to the termiuation of the posterior part or tail , wliicli 

 is also obtuse, but proportioiially much less so than the liead, and is sometimes diniinished to a point. The 

 contour of young planariae tends to the outline of a spherical triangle which gradually alters with their in- 

 crement.« »Mouth in the ander surfiice, nearer to the tail than to the anterior extremity.« »Towards the 

 anterior part are two blackish spots on the upper surface of the body, which . . . are discovered to be two 

 groiips or Clusters of minut jet black sjiecks, of iinequal size and liquewise of unequal niimber in different 

 animals.« 8 — 10 in each Cluster. »These specks approach to a globular figure; some are appareutly con- 

 füunded together; and they occasionally appear siugly, advanced in a straight line frome the respective 

 Clusters.« uWhether tliese specks be truly eyes, or what is their peciiliar use, is uucertain. . .« »Their re- 

 moteness from the mouth may be thought unfavoiirable for aiding the animal to the capture of its prey; 

 and their position so far from the portion first advanced, seems ill calculated for enabling it to avoid 

 danger.« »Planaria »flexilis rather inclines to shun the light. . . . The body is surrounded by a smooth narrow 

 niargin, paler in colour thau the rest , and of a different texture , participating , iu a minor degree , of the 

 gelatiuous consistence, which composes the general substance of the whole genus.« »As the day is warmer, 

 the planaria is larger, and it sensibly diminishes with the approach of a cold.« »It merits conside- 

 ration, that the colour of the entire animal is principally regulated by the tinge of the aliment received«; 

 »Three planariae, after an abstinence of several days, were supplied with the heart and liver of a 

 perch; the sea water was changed, and a quantity of mud put into a glass jar along with them. Next 

 morning a material alteration had ensued: the colour of the largest was altogether altered from its original 

 duU and tawny white, to dark reddish brown. Numerous ramifications, beautifully interlaced, were distri- 

 buted throughout the body, proceeding from the centre to the interior of the narrow margin, into which 

 they did not penetrate, and the size of the body was augmented.« »Some times afterwards, the samc pla- 

 nariae having devoured a green marine nereis, a creature of soft consistence as themselves, their bodies 

 became of a greenish hue, which three or four days were required to obliterate. It is alike with each va- 

 riety of food; the colour is constantly imparted to the animal; and nothing can be more elegant and 

 interesting than its dissemination among the numerous pinnate and delicate shaped vessels performing 

 the fuuctions of nutrition.« Ualyell warnt deshalb, bei der Unterscheidung dn- Arten auf die Farbe 

 zu viel Gewicht zu legen. »All the planariae that have come under my inspection, would 

 seem, to a superficial observer, quite different species in a State of abstinence from what 

 they are in a state of repletion.« »Their voracity is incredible: the whole flexile body is em- 

 ployed in firmly infoldiug the prey: if living, its struggles are vain to get free; it is gradually absor- 

 bed until the capacity of the viscera can receive no more.« Beobachtung über das Schwimmen an der 

 Wasseroberfläche. »These planariae dwell in Society: they are of an extremely pacific nature among 

 themselves, and very inactive, unless when in pursuit of ])rey. Then they may be seen traversing their 

 Clement with a remarkable motion, produced by the successiv opening and closing of the broad anterior 

 part of the body. They generally live half buried in mud.« »On the water becoming fetid, they rise 

 to the surface and endeavour to escape« »If a tail glass jar be fiUed with a promiscuous mixture of mud 

 and vegetables from a fresh water marsh, many of its inhabitants will be seen ascending the sides towards 

 night, though, ou the approach of day, they return to places of concealment.« Beobachtungen über 

 Eiablage (vom December bis Mai). Von jeder Planarie wurden Tausendc von Eiern an der Wand der 

 Gefässe abgelegt. »The Planaria flexilis is one of those beings so eminently privileged, as to preserve 

 animation when divided into sections: If cut asunder, each half acquires the defective organs. At first 

 the posterior portion is quiescent; and a considerable interval elapses before its motion and activity are 

 resumed : the anterior division suffers little, it traverses its dement as if scarce affectcd by the nmtilation ; 

 a thin triangulär Vegetation proceeds from the wound, wliich is gradually enlarged, and at last acquires the 

 exact figure and proportions of the severed parts. The longest period during which I have at once preser- 

 ved these marine Planariae, has exceeded eight months. As accident then deprived me of theim, we are not 

 to couclude on the brevity of their existence.« 



5 6) Tres mince, large, foliacce, plissee, ovalaire; un peu plus etroite en arriere qu'en avant. 

 Points oculiformes noirs, trcs uombreux, formant, vers la partie anterieure du corps, deux trainees dont 

 la partie posterieure est composce de six points plus gros; ä la face inferieure une tache blanchätre, 



