20 MEDUS.E OF THE WORLD. 



The following table defines the characters of the genera ot Codomdae. 



SUBFAMILY No. i. SARSIAN^E. 



With simple marginal tentacles which arise singly from bell-margin. One or all of the tentacles may be rudimentary or absent. 



Tribe I. ANEMIDI. 



Without tentacles or chymifcrous canals. 



Pachycordyle, WEISMANN, 1883; HARCJITT, \^o^=Parvanenius ( ?) MAYER, 1904. 



Medusa without tentacles, marginal sense-organs, radial-canals or circular canal. Hydroid: Pachycordyle ', WEISMANN. 



Tribe II. AMALTHIADI. 



The hydroid is Corymorpha. Medusae have 4 radially placed, rudimentary tentacles and 4 radial-canals. 

 Amalthtza, SCHMIDT, 1854. M.edus*= Amafthaa, HAECKEL. 



With 4 rudimentary tentacles, 4 radial-canals, and ring-canal. Genital products on manubrium. Hydroid: Corvmorpha. 



Tribe III. PENNARIDI. 



Medusae similar to those of Tribe II, but hydroid is Pcnnaria. 

 Pennaria, OKEN, 1815; GOLDFUSS, 1820. 



With 4 rudimentary tentacles, 4 radial-canals, and ring-canal. Genital products within manubrium. Hydroid: Pennaria. 



Tribe IV. PSEUDOPENNARIDI. 



Medusa similar to those of Tribes II and III, but hydroid is Trichorhiza. 

 Trick or kiza, RUSSELL, 1906. 



Medusa similar to Pcnnaria, but hydroid is Trichorhiza. 



Tribe V. EUPHYSIDI. 



With small or rudimentary tentacles situated at bases of all but one radial-canal, and with one or more well-developed tentacles 

 situated at base of remaining radial-canal. Bell may or may not possess an apical projection, or an axial canal extending 

 into it from stomach-cavity. 

 Sleenstrupia, FORBES, 1846= Euph \sa, FORBES, 1848; Eufthysora, MAAS, 1905. 



The bell is radially symmetrical and the 4 radial-canals are all of equal length, i long and 3 short tentacles. Hydroid: 



Corymorpha. 

 ffybocodon, L. AGASSIZ, 1862= Amphicodon, HAECKEL, 1879. 



The bell is asymmetrical. One of the 4 radial-canals is long, the one opposed to it short, and the two other canals of inter- 

 mediate length. One long tentacle arises from the base of the long radial-canal, while the other 3 tentacles are short 

 In old medusae of Hybocodon one is apt to find 2 or more tentacles at the base of the long radial-canal, and the medusa, 

 is in the Amphicodon stage. Hydroid: Hybocodon. 

 Microcampana y FEWKES, 1889. 



With 6 radial-canals and 6 tentacles, one of which is well-developed and 5 arc rudimentary. Hydroid unknown. 



Tribe VI. DICODONIDI. 



With 2 well-developed, diametrically opposite tentacles, and 2 rudimentary tentacles. With or without an apical projection 



and with or without axial canal extending upward from the stomach into apex of bell. 

 Dicoelonium s HAECKEL, 1879. 



With 4 simple radial-canals and 4 radially placed tentacles; 2 of the tentacles are long, and 2 short. Gonad is ring like 

 and surrounds stomach. No lines of nettling cells over exumbrella. 



Tribe VII. SARSIADI. 



Bell radially symmetrical. With 4 equally-developed, unbranched, marginal tentacles. With or without an apical projection, 

 and with or without an axial canal extending upward from stomach into apex of bell, (i) The manubrium is encircled 

 by a single ring-like gonad. (2) With 2 or more ring-like gonads upon the manubrium. 

 Sarsia, LESSON, i$4$ = S\ndict\on t A. AGASSIZ, 1862; Codonium t HAECKEL, 1879. 



Manubrium slender and tubular. Each tentacle-bulb bears an abaxial, ectodermal ocellus. Hydroid: S \ncoryne. 



Also Staiindta. 

 Hydrichthys, FEWKES, 1888. 



Medusa similar to Sarsia, but without ocelli upon the tentacle-bulbs. Hydroid: Hvdrichthys. 

 Eneodonium, HARTLAUB, 1907. 



Medusa similar to Sarsia, but stomach is mounted upon a gelatinous peduncle, and tentacles end each in a knob. 

 Ectopleura, L. AGASSIZ, 1862. 



8 longitudinal lines of nematocysts extend from bases of tentacles to apex of bell. Hydroid: Ecto pleura. 

 Corynitis, McCRAov, 1857. 



Manubrium cruciform in cross-section, and bound to the 4 radial-canals by hollow mesenteries. 4 radially placed marginal 

 tentacles which are covered with wart-like clusters of nematocysts. Their basal bulbs bear ocelli. Hydroid: Syncoryne. 

 Slabber ia, FORBES, 1846= Difwrena, McCRADY, 1857. Dif>urena + Bathvcodon, HAECKEL. 



Similar to Sarsia, but with two or more ring-like gonads upon the manubrium. Hydroid: S\ncor\ne. 



SUBFAMILY No. 2. MARGELOPSINJE. 



With 4 radiallv-placed clusters of marginal tentacles. No oral tentacles. Gonads ring-like, and encircling the manubrium. 

 MargelopsiSy HARTLAUB, 1897. 



Marginal tentacles are grouped in 4 radially-situated clusters. Gonad ring-like, and surrounds manubrium. No oral 

 tentacles, mouth is a simple round opening. Medusae develop by budding from a free-floating hydranth, A/drgr/o/fj/i. 

 This interesting genus recalls the Bougainvillidi in its radially situated clusters of marginal tentacles. It resembles the 

 Codonidts in its ring-like gonad, and in the absence of prominent lips and oral tentacles. 

 Pelagohydra, DENDY, 1903. 



Medusa similar to Margelopsi* but hydroid is Pelagohydra, and differs from hydroid of Margelopsn in that tentacles arise 

 at irregular intervals from the sides of the hydranth and are not arranged in definite verticils as in Margelopsis. 

 Hydroid is pelagic. 



