THE COELENTERATES AND CTENOPHORES 103 



a. Suborder Semostomae. — Four large perradial arms surround 

 mouth. Aur^a, Cyanra. 



b. Suborder Rhizostomae. — No marginal tentacles; many- 

 mouths. Stomolophus. 



III. Class Anthozoa. — Polyp only; esophagus; mesenteries. 



A. Subclass Zoantharia. — Numerous mesenteries and tentacles. 



1. Order Actinaria. — Solitary" ; no skeleton. Metridium, Sagartia, 

 Crihjjua, Ccrianthus, Edwardsia. 



2. Order Madreporaria. — Colonial; calcareous skeleton. Astrgji,' 

 gia, Orbicella, Meandrina, Coeloria, Favia, Madrepom, Pontes. 



3. Order Antipatharia. — Colonial; treelike horny skeleton. Anti- 

 pathcs, Cirripathes. 



B. Subclass Alcyonaria. — Eight mesenteries and branched tentacles. 



1. Order Alcyonacea. — Skeleton of spicules or small, irregular 

 bodies; axial rod lacking. Tubipora, Alcyonium. 



2. Order Gorgonacea. — Treelike; calcareous or horny skeleton. 

 Gorgofda, CoraUium, Euplexaura. 



3. Order Pennatulacea. — Colony with one end usually buried in 

 sea-l3ottom. RcjiiUa, Pennatida, Plilosarcus. 



B. Phylum Ctenophora. — Eight meridional bands of ciliated plates; adhe- 

 sive cells; centralized nervous system; pelagic. 



I. Class Tentaculata. — Typically with two aboral tentacles. 



1. Order Cydippida. — Body ovoid or pear-shaped; two retractile 

 tentacles arising from aboral tentacular sacs. Pleurobrachia, 

 Mnemiojisis. 



2. Order Lobata. — Two large oral lobes; no tentacular sacs; 

 numerous lateral tentacles. Bolinopsis, Deiopea. 



3. Order Cestida. — Pdbbonlike; two tentacular sacs and numerous 

 lateral tentacles. Cestus. 



n. Class Nuda. — No tentacles; no oral lobes. 



1. Order Beroida. — Laterally compressed; gullet occupies most of 

 interior of body. Beroe. 



References 



(See general references at close of Chapter I) 

 Agassiz, a. 1865. "North American Acalephae." Mus. Co?np. Zool., 



Harvard, Illustr. Cat. 2. 

 Agassiz, L. 1850. "Contributions to the Natural History of the Acalephae 



of North America." Mem. Amer. Acad. Arts Sci., Boston, 4: 221-374. 

 . 1860-1862. "Contributions to the Natural History of the United 



States." Boston. 

 Chun, K. 1880. "Die Ctenophoren des Golfes von Neapel und der 



angrenzenden Meeres-Abschnitte." Vol. I, Fauna und Flora des 



Golfes von Neapel. 

 Haeckel, E. 1879-1880. "System der Medu.sen. I, Cra.spedoten; II, 



Acraspeda." Jena. 

 Mayer, A .G. 1910. "Medusae of the World." Carnegie Inst., Wash- 

 ington, Publ. 109. 



