APPENDIX 833 



PHYLUM 5. COELENTERATA. Polyps and medusae. Radiata without combs and with 

 nematocysts. 

 CLASS 1. HYDROZOA. Medusae with a vehmi, polyps with simple gut. 

 Order 1. Trachylina. Gotiioneiims, fresh-water jellyfishes. 

 Order 2. Hydroidea. Obelia, hydras. 

 Order 3. Siphonophora. Physalia. 



Orders 4 and 5. Milleporina and Stylasterina. Colonial polyps that se- 

 crete massi\e limestone exoskeletons. 

 CLASS 2. SCYPHOZOA. Medusae without a velum, polyps with four internal 



partitions. Five orders. Aurelia. 

 CLASS 3. ANTHOZOA. Polyp with 6, 8, or more internal partitions. No 

 medusa. 

 Subclass 1. Alcyonaria. Eight feathery tentacles and 8 internal partitions. 

 Often with an internal skeleton. Six orders. Sea fans, precious 

 coral. 

 Subclass 2. Zoantharla. Internal partitions 6 or more, tentacles simple. 

 Five orders, including: 

 Order 1. Actinaria. Sea anemones. 

 Order 2. Madrepororio. True corals. 



PHYLUM 6. PLATYHELMINTHES. Flatworms. Well developed mesoderm with nephridia, 

 a single opening foi mouili and anus. 

 CLASS 1. TURBELLARIA. Free-living, epidermis ciliated in adult. 

 Order 1. Acoela. No gut cavity. 

 Order 2. Rhabdocoala. Simple tubular gut. 

 Order 3. Alloeocoela. Cut has one main branch with small side 



branches. 

 Order 4. Tricladida. Cut has three branches. Planaria, Diigesia. 

 Order 5. Polycladida. Gut has many main branches. 

 CLASS 2. TREMATODA. Fhik.es. Parasitic, willi o\d\ sucker, epidermis lacking. 

 Order 1. Monogenea. Fctoparasitic with a one-host life cycle. 

 Order 2. Aspidobofhria. Fndoparasitic with a one-host cycle. 

 Order 3. Digenea. Fndoparasitic with at least a two-host cycle. 

 Srhi^tosotna. 

 CLASS 3. CESTODA. Tapeworms. Endoparasites with no epidermis, no gut. 

 Subclass 1. Cestodarl^. Body not segmented. Two orders. 

 SuBCi^ss 2. Eucestoda. Body segmented into proglottids. Nine orders, of 

 which the follovving two are foiuid in mammals: 

 Order 1. Bothriocephaloidea. Fish tapeworms (fish carry cercoid stage). 

 Order 2. Taenioidea. Pig and beef tapeworms, etc. 



PHYLUM 7. ASCHELMINTHES. Pseudocoelomates with tendencies toward extreme cellu- 

 lar differentiation and loss of regenerative powers. Body covered 

 by a cuticle. 

 CLASS 1. ROTIFERA. Rotifers. Wheel organ around mouth and jaws in phar- 



vnx. Three orders. Philodina, Rotaria. 

 CLASS 2. GASTROTRICHA. Gastrotrichs. Cilia on ventral surface, pharynx 



nematode-like. Two orders. 

 CLASS 3. KINORHYNCHA. Body segmented with eversible spiny head. One 



order. 

 CLASS 4. NEMATODA. Roundworms. Triradiate pharynx and modified nephri- 

 dia. About 17 orders, including: 

 Order 1. Rhabditoidea. Vinegar eel. 

 Order 2. Ascaroidea. Ascaris, other large intestinal roundworms. 



