222 CLASS VIT. 



Phalanx I. fihabdoccda. Intestine simple, cylindrical, not ex- 

 sertile from the mouth. Body elongate, roundish or depressed. 



Prostoma OERST. (not DUGES), Gyrator EHRENB. Oral aperture 

 anterior terminal. 



Sp. Prostoma lineare OERST., Gyrator hermaphroditus EHRENB., Abhandl. 

 der AJcad. der Wissensch. zu Berlin, 1835, Tab. I. fig. 2. 



Vortex EHRENB. 



Sp. Vortex Iruncatus, Planaria truncata, Zool. danic. Tab. 106, fig. i, a, b, 

 EHRENB. 1. 1. figs. 3, &c. 



Derostoma OERST. (DuGES in part). 



Mesostoma DUGES, OERST. Body depressed, transparent; oral 

 aperture annular, rotund, situated a little in front of or in the middle 

 of the body. Eyes two anterior. 



Sp. Mesostoma Ehrenbergii, Planaria tetragona MUELL., Fasciola qitadrangu- 

 laris PALL., Spicil. Zool. x. Tab. i. fig. 12; Zool. danic. Tab. 106, 

 figs, i 5 ; FOKKK, Ann. des Wiener Museums, i. 1836, pp. 191 206, Tab. 

 xvili. This species has been elaborately investigated by the last-named 

 writer ; it undergoes various changes of form ; from the flat form a quad- 

 rangular arises, as though the animal were about to divide itself in the 

 length. PALLAS had already observed this Planaria more than 70 years 

 earlier at Sorgvliet, and it has lately been found again at Leyden by HERR 

 HERKLOTS. 



Strongylostoma OERST. 



Typhloplana EHRENB. 



Macrostoma OERST. 



Microstoma OERST. (Vid. SCHULTZE quoted p. 203.) 



Convoluta OERST. 



Phalanx II. Dendroccela. Nutrient tube branched. Body 

 depressed. (Dendroccela and Cryptocmla OERST.) 



a) Appendages numerous, tubular or papillce on, the back. 



Thysanozoon GRUBE, Eolidiceros QUATREF. Eyes sessile, nu- 

 merous ; body excised anteriorly and cloven into two tentacles. 



Sp. Thysanozoon Brocchii, Solid. Brocchii QUATREF. 1. 1. PI. 5, fig. i, (perhaps 

 the same species as Thysanozoon Diesingii GRUBE, Aclinien, Echinodermen 

 u. Wiirmer, fig. 9) ; in the Mediterranean. The intestinal canal has here a 

 retiform division. 



