170 INVEBTEBRATB MORPHOLOGY. 



organs with common opening. Bunda, Planaria, Phagocata, 

 Dendroccelum, Bdelloura, Bipalium, Synexlidium. 

 5. Order PoZyctocZea.— Digestive tract brailched, the primary branches 

 being numerous; male and female organs having separate open- 

 ings. 



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



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



lochus. 

 II. Class Teematoda. — Ecto- or endoparasites; ectoderm not ciliated; 

 with digestive tract and suckers. 

 1. Order PoZystomece.— Suckers more than two; development direct; 

 usually ectoparasites. Polystomum, Sphyranura, Tristomum, 

 Qyrodactyhis. 

 3. Order Bistomea. — Suckers one or two; development indirect; usu- 

 ally endoparasitic. Bistomiim, Monostomum. 



III. Class Cestoda. — Endoparasites; ectoderm without cilia; no digestive 



tract or mouth ; usually strobilated. Taenia, Bothriocephalus, 

 CaryophyllcBus, Ligula, Tricenophorus, Archigetes. 



IV. Class Nemertina. — Ectoderm ciliated; not parasitic; anus present; 



with protrusible proboscis. 



1. Order Palmonemertini. — Lateral ciliated funnels shallow; nervous 



system imbedded in ectoderm; proboscis without stylets. Cari- 

 nella. 



2. Order Schizonemertini. — Lateral ciliated funnels deep; nervous 



system imbedded in muscle-layer; proboscis without stylets. 

 Cerebratulus. 



3. Order Roplonemertini. — Lateral ciliated funnels deep; nervous 



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

 stemma, Amphiporus. 



4. Order MalacohdelUna. — No lateral ciliated funnels; proboscis 



without stylets. Malacobdella. 



LITERATURE. 



turbellama. 



L. von Graff. Monograplde der Turhellarien : 1. Rhahdocceliden . Leipzig, 1883. 



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



L. BShmig. Untersuchungen uber rhabdocoelen Turhellarien , 11. Zeitschr. fur 

 wissensch. Zoologie, Li, 1890. 



W. M. Woodworth. Gontributions to the Morphology of the Turbellaria, I. Bul- 

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



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

 XI, 1884. 



W. M. Wheeler. Syncmlidium pellueidum, a new marine Triclad. Jour, of 

 Morphology, ix, 1894. 



