A 1. Familie: Procerodidae. 329 



Da die Verschmelzung der hinteren üarmäste zufällig sein dürfte, so ist Hai.lez im 

 Unrecht, wenn er macrostoma zu Cercyra stellt, um so mehr, als, wie oben p 294 gezeigt, 

 auch bei Cercyra die hinteren Darmäste normalerweise nicht verschmolzen sind. 



Böhmig zählt P/a?i. ('?)?«atros<o/«flDarw. zu den »ungenügend charakterisirten Species« und gibt 

 »aus Darwin's Beschreibung nur die für die Identificirung wesentlichen Stellen« wieder. (Bei der 

 Umrechnung von Darwin's Grössenangaben in mm gibt er irrthümlich 5 mm und 0,13 mm anstatt 

 4,3 und 1,3 mm an.) 



Speciesbeschreibung (s. Textf. 72). 



"External alimentary orifice situated in the posterior halfofbody: mouth-sucker nearly 

 subcylindrical, bell shaped, very long; when contracted within the body it lies in a Serpentine 

 Position ; whcn partly protruded it has the figure as represented ; when fully extended it tapers 

 only slightly from its mouth to its base, and is so long, that the animal can pass it from the 

 under surface over the entire width of its back. 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 which the 

 mouth-sucker and its external orifice are situated. The three main branches 

 receive the mcss-like siibdivision of the intestinal cavity, which reach all round 

 nearly to the margin of the body. The main, medial, intestinal cavity ends at 

 the anterior extremity in a small, opake, wedge-formed mass; on each sidc 

 of which, nearly on the dorsal surface a black ocellus is situated. Between the 

 lateral branches on each side of the medial cavity, seven or eight internal 

 spherical cavities lie, including opake balls, which I presume are immature Fig- ''2. Prot. 



. Till macrostoma, 



ova; the anterior ones were most developed: they were not present in the nach Dakwin. 

 smaller specimens, or in all the fuU-grown ones. I was unable to discover any 

 genital orifice, though no doubt one or two exist: near the posterior extremity (at B) there 

 was a colourless space, but I could not see any orifice. Anterior extremity Square, trvincate, with 

 edges thin and prehensile; the animal attaches itself by this part, almost like a leech with 

 its sucker, and thus drags its body: posterior extremity broadly rounded. Above, faintly co- 

 loured brownish purple in Striae, with a colourless space over the alimentary orifice. Length 

 Vioths; breadth "/looths of an inch. 



Hab. Congregated in numbers under stones, in brackish water; Chonos Archipelago 

 (west coast of S. America) (December). 



The arrangement of the main branches of the intestinal cavity is the samc as in the 

 terrestrial Planariac, with the exception of the two posterior branches being united near the 

 extremity of the body into a ring, which structure I have not met with described in any other 

 species. Hence this species probably ought to form the type of a new subgenus. I may 

 here mention, that I found amongst these Islands an elongated marine species (with a very 

 distinctly formed head placed on a narrow neck) which had the power of crawling either 

 backwards or forwards, — a power I have never seen in any other species." 



49 



Zool, Station zu Neapi.!, Fauna und Flora, Golf von Neapel. Triciaden. 



