ANNULOSA. 



39 



ORDER III. TURBELLARIA. 

 Sub-ord. 1. Planarida. 



Section A. Khabdoccela. Prostomum, Opisthomum, Mac- 

 rostomum, Convoluta. 



Section B. Dendrocoala. Planaria, Geoplana, Lepto- 

 plana (fig. 32), Polycelis. 



Sub-ord. 2. NEMERTIDA (Ribbon-worms). 

 Section A. Anopla. Linens, Borlasia. 

 Section B. Enopla. Nemertes, Tetrastemma. 

 Section C. Pelagoneinertida. Pelagonemertes (fig. 33). 



(Max Schultze, Beitrdge zur Naturgeschichte der Turbdlarien, Greifswakl, 

 1851 ; Oersted, Entwurf einer Systematischen und Speciellen Beschreibung 

 der PlattTwrmer, Copenhagen, 1844 ; M'lntosh, A Monograph of the Brit- 

 ish Nemerteans, Kay Society, 1873-74.) 



irtx 



Fig. 33. Nemertida. Pelagonemertes Rollestoni, a pelagic Nemertid, viewed from the ven- 

 tral surface, p, Proboscis, partially protruded ; m, Opening of the mouth ; i, Alimentary 

 canal, with its lateral diverticula, shaded darkly ; s, The sheath of the proboscis, more lightly 

 shaded ; n, The nerve-ganglia, placed one on each side of the mouth, and each giving off 

 long lateral and backwardly-directed branch, external to which, on each side, is a row of 

 ovaries (o). (After Moseley.) 



