5 YSTEMA TIC SUR VE Y — SC YPHOZOA. j 5 1 



their power of taking up lime, and so forming "corals." The colonies 

 are complex and divergent, the reproductive persons are probably sessile 

 gonophores, but a simple male medusoid has been described. Mille- 

 pora, Stylaster. 



(c) Trachymedusae. — These exist only in the medusoid form, and are 

 divided into two groups, Trachomedusse and Narcomedusce, according 

 to the position of the gonads. 



Geryonia, Carmarina, Cunina, Aeginopsis. 



2. Order Siphonophora. — Free - swimming colonies of modified 

 medusoid persons (medusomes), with much division of labour. 



Physalia (Portuguese man-of-war), Diphyes, Velella, Porpita. 



B. Class Scyphozoa. 



There are two types — polypoid and medusoid — very rarely occurring 

 in one life history. The gastric cavity has partitions with gastric or 

 mesenteric filaments, and there is an ectodermic gullet. The mesoglcea 

 generally contains migrant cells. The reproductive cells are endo- 

 dermic. 



I. Sub-class Scyphomedusse or Acraspeda — 



Jelly-fish with gastric filaments, sub-genital pits, and no velum — 



(1) Lucernariue. — Sessile forms. Lucemaria. 



(2) Discomedusce. — Active forms, often with complicated life 



history. Aurelia, Pelagia, Cyanea, Rhizostoma. 



(3) CubomedusEe. — Forms with broad pseudo-velum, and 



other peculiar features. Charybdea. 



(4) Peromedusse. — Forms with four tentaculocysts only. 



Pericalpa. 



II. Sub-class Anthozoa, or Actinozoa — 



Polypoid forms with well-developed gullet and septa, and 

 circumoral tentacles. 



( 1 ) Zoantharia or Hexacoralla. 



(a) Actiniaria. Sea-anemones. 



Actinia, Anemonia, Tealia, Cerianthits. 



(b) Madreporaria. Stone or reef corals. 



Astrtza, Madrepora, Fungia, Maandrina. 



(c) Antipatharia. "Horny" black corals, with an 



axial skeleton, and occasional dimorphism 

 between nutritive and reproductive "persons." 

 Antipathes. 



(2) Alcyonaria or Octocoralla. 



Alcyonium (Dead-men's-fingers), Tubipora (Organ- 

 pipe coral), Corallinm (Red coral), Gorgonia, Pen- 

 natala (Sea-pen), Monoxenia (non-colonial). 



C. Class Ctenophora. 



Delicate free - swimming organisms, generally globular in form, 

 moving by means of eight meridional rows of ciliated plates, or comb- 



