502 Dritter Abschnitt. Systematik. 



mouth-suckers are quite similar; tliey are miich shallower tlian those of any other species of the family 

 wliicli I liave seen: their membranous edges are very thin, narrow, transparent and sinuous: in the act of 

 contraction they become folded in a complicated manner, like the bud of a flower. I was able easily to 

 dissect them out of the body, and they retained, in the eharacteristic manner described by Dugfis, and as 

 in the terrestrial Planariae, an extreme degree of irritability and contractile power, long after the rest of 

 the body had ceased to live. In the elliptic space surrounding the two mouth-suckers when contracted, 

 and between the mouths of the lateral, branching, intestinal cavities, innumerable ova are arranged in 

 groups from two to four in each ; these are represented in the drawing only by double dots. These ova 

 were easily separated ; they are splierical •''/soo ''"' of an inch in diameter, and contain a central opake mass- 

 in the posterior clear space there are two minute, but quite distinct, orifices [D and E], which I do not 

 doubt are the reproductive pores : into this clear space a large fork, filled with opake white matter , enters, 

 as is shown, in the drawing; this matter consists of minute, white globules in chains, imperfeetly united 

 together : I believe these are immature ova, and hence I suppose that the fork is the ovarium , from M'hich 

 the ova pass into the clear Spaces surrounding the mouth-suckers and are there matured. The ocelli are 

 black and circular, and are arranged in four groups, two of which are round, and two in elongated bands 

 inclined to each other : the ocelli in the bands are not seated on the dorsal surface but deep within the 

 body, near the ventral surface. Colour pale »tile-red«, darkest on the dorsal ridge, with colourless Spaces 

 over the genital orifices and over the ocelli. Length ^Vioo *''^ of an inch; breadth of anterior part of body 

 Yio *'"*; of posterior part Yio *'' of an inch. — Hab. Under stones in tidal pools, Chonos Archipelago (Western 

 S. America. December). — This animal is very active, can crawl quickly, and can swim well by the move- 

 meuts of its thin marginal edges; it can adliere firmly to stones.« 



Stimpson macht in seinem Prodromns (1857. 78. pag. 1) über diese Art, sowie über 

 Planaria bilobata Leuck. und Centrostomum incisum Diesing folgende, wie mir scheint, un- 

 richtige Bemerkung : »Forsitan Planariae in re sese bipartiendi sunt.« 



10. Genus. Trigonoporus nov. gen. 



Mit ziemlich verlängertem Körper. Mundöffnung etwas hinter der Mitte 

 der Bauchseite. Pharynx ziemlich stark gefaltet. Der Hauptdarm erstreckt 

 sich vorn und hinten weit über die Pharyngealtasche hinaus; vorn endigt er 

 hinter dem Gehirn; hinten läuft er über die Begattungsapparate hinweg bis 

 gegen das hinterste Leibesende. Sehr zahlreiche Paare von Darmastwurzeln. 

 Männlicher Begattungsapparat ohne Samenblase, mit unbewaffnetem, kegel- 

 förmigem, in eine einfache Penisscheide eingeschlossenem Penis und grosser 

 Körnerdrüsenblase. Die Vasa deferentia münden vermittelst eines gemein- 

 samen Endstückes an der Grenze zwischen Körnerdrüsenblase und Penis in 

 den Begattungsapparat ein. Weiblicher Begattungsapparat ohne Bursa copu- 

 latrix; Eiergang nach hinten in einen in regelmässigen Abständen eingeschnür- 

 ten Canal verlängert, der hinter der weiblichen Geschlech tsöffnung nach aus- 

 sen mündet. Umgegend der weiblichen Geschlechtsöffnung zu einem Haft- 

 organ umgewandelt. Augen in grosser Anzahl zerstreut im ganzen vordersten 

 Körpertheil zwischen Gehirn und vorderem Leibesende. 



