Das System der Pol)claden. 6(J9 



Hab. Opeu ocean, lat. 5" S. loug 33" W. February) at the distaiice of 150 iiiiles froni the iiearest 

 part of S. America aud SO miles from the small Island of Fernando Noronlia.« 



Die Species ist nach dieser Beschreibung völlig unverständlich. Sollte die Auffassung 

 der Oeflfnungen des Körpers wirklich richtig sein, so hätten wir es mit dem Repräsentairten 

 einer besonderen, ganz abweichenden Polycladenfamüie zu thun. 



201. Plana ria (?) incisa Darwin. 



Planaria y^) incisa, ') Darwin 1s44 41. pag. 24S— 249. Tab. V. Fig. 3. 

 Centrostomum incisum, Diesing 1S50. 56. pag. 200. — 18G2. 89. pag. 543. 



1; »Body oval, very much depressed, higlily contractile; margin sinuons, anteriorly deeply indented, 

 posteriorly less so. Ocelli very numerous aud crowded together in several rows on tbe indented anterior 

 (as is known by its progression) margin. Along tbe centre of the body an intestinal vessel extends, and in 

 the middle of this there is a well-closed orifice, througb which the animal cau protrude a thin, much- 

 folded, sinuated mouth-sucker ; this when fully expanded is quite as wide as the body. Posteriorly, on each 

 side of the central vessel, there is a mass, apparently of immature ova. Near the posterior extremity there 

 is a second subterminal orifice, through which, when the animal was placed in spirits, a little globular mass 

 was protruded, like a small, much contracted mouth-sucker. Near to the anterior extremity there are two 

 sUghtly retractile paps, with orifices, of which the anterior one is the largest. From tliis poiut divergiug 

 rays intestinal cavities?, are sent of, which reach nearly to the margin of the entire body: when the 

 animal contracts itself , the back is raised in slight ridges , correspondiug ^^•ith these rays. This species, 

 therefore, has four orifices on its uuder surface. Back fiuely reticulated with brownish purple. Length 

 1 inch; breadth three-quarters of an inch. — Hab. Under stones on the sea-beach. St. -lago; Cajje Verd 

 Archipelago February). Tliis species is exceedingly active and irritable in its habits : it lives, like a Nereis, 

 under stones firmly imbedded in the beach at low-water mark. It has the power of adhering with great 

 tenacity to smooth stones: another allied species had the same power, could also smm well by a vertical 

 movement of its body, and frequently roUed itself into a ball. With respect to the four orifices: I presume. 

 as in the P. formosa, the two anterior ones belong to the reproductive System. The central orifice un- 

 doubtedly is the mouth: the posterior one would naturally be thought to be the anus; but I am doubtful 

 of this, considering the little globular body which was protruded through it, and from the existence in the 

 following allied genus of a double mouth.« 



Die Organisation dieses Thieres ist mir nach der DARwrx'schen Abbildung und Be- 

 schreibung ganz unverständlich. Stimpson (1857. 78. pag. 1) glaubt, dass dasselbe in Zwei- 

 theüung begriffen war. 



202. Planaria (?) formosa Darwin. 



Planaria ?) formosa, Darwin 1844. 41. pag. 247. 



Leptoplana formosa, Diesing 1S50. 56. pag. 199. — 1862. 89. pag. 541. 



jiBody much depressed, oval. In the posterior half, on the under side, there is a very large ali- 

 mentary orifice with folding lips but apparently with no exsertile mouth-sucker), from which the two 

 main intestinal cavities brauch. Near the anterior extremity there is a minute orifice, aud between it and 

 the mouth a second orifice; these the animal can dilate aud contract; they lie over an opake, wedge- 

 formed, internal mass, and form, I presume, two genital orifices. Back dotted with purplish red, with a 

 central band of > vennilion red^c, edged with white : this band sends ofl" three branches on each side ; at the 

 extremity of each of the two anterior branches there is a longitudinal group of black ocelli, and before 



Zool. Station z. Neapel, Fauna und Flora, Golf von Neapel. XI. Pölycladen. 77 



