170 INVERTEBRATE MORPHOLOGY. 



organs with common opening. Gfunda, Planaria, Phagocata, 

 Dendrocoelum, Bdelloura, Bipalium, Syncoslidium. 

 5. Order Polycladea. Digestive tract branched, the primary branches 

 being numerous; male and female organs having separate open- 

 ings. 



(a) With terminal sucker (Cotylea). Thysanozoon, Eurylepta. 

 (6) Without sucker (Acotylea). Planocera, Leptoplana, 8ty- 



lochus. 



II. Class TREMATODA. Ecto- or endoparasites; ectoderm not ciliated; 

 with digestive tract and suckers. 



1. Order Polystomece. Suckers more than two; development direct; 



usually ectoparasites. Polystomum, Sphyranura, Tristomum, 

 Oyrodactylns. 



2. Order Distomece. Suckers one or two; development indirect; usu- 



ally endoparasitic. Distomum, Monostomum. 



III. Class CESTODA. Endoparasites; ectoderm without cilia; no digestive 



tract or mouth; usually strobilated. Tcenia, Bothriocephalus, 

 CaryophyllcBus, Ligula, Tricenophorus, Archigetes. 



IV. Class NEMERTINA. Ectoderm ciliated; not parasitic; anus present; 



with protrusible proboscis. 



1. Order Palceonemertini. Lateral ciliated funnels shallow; nervous 



system imbedded in ectoderm; proboscis without stylets. Cari- 

 nella. 



2. Order Schizonemertini. Lateral ciliated funnels deep; nervous 



systetn imbedded in muscle-layer; proboscis without stylets. 

 Oerebratulus. 



3. Order Hoplonemertini. Lateral ciliated funnels deep; nervous 



system within muscle-layer; proboscis with stylets. Tetra- 

 stemma, Amphiporiis, 



4. Order Malacobdellina. No lateral ciliated funnels; proboscis 



without stylets. Malacobdella. 



LITERATURE. 



TURBELLAKIA. 



L von Graff. Monographic der Turbellarien .: 1. RhftMocwliden. Leipzig, 1882 



L. von Graff. Die Organisation der Turbdlaria accela. Leipzig, 1891. 



L. Bb'hmig. Untersuchungen fiber rhabdoca'len Turbellarien, II. Zeitschr. fiir 

 wissensch. Zoologie, LI, 1890. 



W. M. Woodworth. Contributions to the Morphology of the Turbdlaria, I. Bul- 

 letin of the Museum of Comp. Zool., xxi, 1891. 



A. Lang. Die Polycladen. Fauna u. Flora des Golfes von Neapel. Monogr., 

 xi, 1884. 



W. M. Wheeler. Syitea'lidium pellucid um, a new marine Tridad. Jour, of 

 Morjjhology, IX, 1894. 



