6 MEDUS.E OF THE WORLD. 



CORYNITIS, McCrady, 1857. 



Four knobbed tentacles. Manubrium cruciform in cross-section. Ocelli upon tentacle- 

 bulbs. Hydroid: Syncoryne (Hargitt). 



SLABBERIA, Forbes, lB^6 = Slabberia + Dif>urena + BathycoJon, Haeckel, 1879. 



Four knobbed tentacles. Manubrium tubular and encircled by two or more ring-like 

 gonads. Hydroid: Syncoryne. 



Subfamily No. 2, MARGELOPSIN^E. 



Four radially placed clusters ot marginal tentacles. No oral tentacles. A ring-like 

 gonad encircles the stomach. Four simple, unbranched radial-canals. Hydroids are pelagic 

 Tubularians, and the medusae arise by budding from their sides. 



MARGELOPSIS, Hartlaub, 1897. 



Characters of the medusa are those of the subfamily. Hydroid: Margelopsis, in which 

 the tentacles are disposed in definite circlets. 



PELAGOHYDRA, Dendy, 1903. 



Medusa similar to Margelopsis. Hydroid: PelagohyJra. Its tentacles arise irregularly 

 from sides of the hydranth, and are not disposed in definite circlets. 



Family No. 2, CLADONEMID^E. 



Tentacles branch dichotomously or complexly, or give rise to a linear series of nematocyst- 

 bearing filaments along their abaxial sides. Gonads ring-like, or segregated upon the inter- 

 radial and adradial sides of the manubrium. 



Subfamily No. i, PTERONEMINJE. 



Manubrium without oral tentacles. 



ZANCLEA, Gegenbaur, l8^6 = Zanclea + Gernmaria, Haeckel, 1879. 



With two or four tentacles, each of which gives rise to an abaxial row of nematocyst- 

 bearing branches. With meridional rows of nettle-cells upon the exumbrella. 

 No ocelli upon the tentacle-bulbs. No brood-pouch above the stomach. Hydroid: 

 Gemmaria McCrady; Allman. 



ZANCLEOPSIS, Hartlaub, 1907. 



Similar to Znticlea, but without meridional lines of nettle-cells over the exumbrella. With 

 ectodermal ocelli upon the outer sides of the tentacle-bulbs. 



PTERONEMA, Haeckel, 1879. 



Similar to Zanclea, but with a brood-sac above the stomach. Four tentacles. 



ELEUTHERIA, Ouatrefages, 1842. 



Four to six bifurcated tentacles, and an equal number of simple unbranched radial- 

 canals. There is an ectodermal brood-sac above, but not connected with the stomach. 

 The medusa is hermaphroditic and the germ-cells develop in the brood-sac. Hydroid: 

 Clavatella Hincks. 



MNESTRA, Krohn, 1853; Giinther, 1903. 



Degenerate medusa parasitic upon Phylhrrhoe. Four to no tentacles, each with an 

 abaxial line of nettle-warts. Four perradial meridional lines of nettle-cells over 

 the exumbrella. Four radial-canals. Throat is blocked by a cavernated mass of 

 entoderm. 



Subfamily No. 2, DENDRONEMIN^). 



Manubrium with oral tentacles. 



CTENARIA, Haeckel, 1879. 



Two marginal tentacles with abaxial filaments. Four bifurcated radial-canals. Simple 

 oral tentacles. Brood-sac above the stomach. 



