52 THE HYDROMEDUSAE 



CLASSIFICATION AND LIST OF THE GENERA OF 

 HYDROMEDUSAE. 



It is not at present possible to furnish a satisfactory classification of 

 the Anthomedusae and Leptomedusae. The systems of Hincks and ot 

 Allman are based on hydroid structure, that of Haeckel on medusoid 

 structure ; our knowledge of the ontogenetic connection between indi- 

 vidual hydroids and medusoids is at present so small that any attempt to 

 combine the two systems must necessitate failure. The double systems, 

 hydroid and medusoid, are therefore here given separately ; where 

 practicable, each generation has the corresponding generation appended in 

 brackets ; but even in the few cases here cited, the assignment of hydroid 

 to medusoid, and contrariwise, is often a matter of inference rather than 

 of proof. No attempt has been made in the present article at a critical 

 treatment of the current systems. The chief authorities utilised in this 

 classification are Allman (2), Haeckel (4, 39), Hincks (7), Moseley (37). 

 Another system of the Anthomedusae is to be found in Vanhbffen's Versuch 

 einer natt'irliche Gruppirung der Anthomedusm, Zool. Anz. xiv. 1891. 

 Several genera are thrown together and medusoids assigned to hydroids 

 on the authority of Browne's British Hydroids and Medusae (Proc. Zool. 

 Soc. 1896). 



NOTE. + unites various hydroid genera attributed to the same medusoid genus, or various 



medusoid genera attributed to the same hydroid genus. 

 [ ] Square brackets indicate the corresponding medusoid genus in the hydroid scheme, or the 



corresponding hydroid genus in the medusoid scheme. 

 = indicates a synonym. 

 S indicates a sessile gonophore, in contrast to a free-swimming medusoid. 



CLASSIFICATION OF HYDROMEDUSAE. 



ORDER 1. Anthomedusae = Gymnoblastea. (For definition, see p. 11.) 

 (a). Medusoid Scheme. 



FAMILY 1. CODONIDAE. Genera Codonium, Hkl., + Sarsia, Lesson, 

 + Syndictyon, A. Agass., [Syncoryne] ; Ectopleura, L. Agass., [Ectopleura] ; 

 Dipurena, M'Crady, = Slabberia, Forbes ; Bathycodon, Hkl. ; Dicodonium, 

 HkL ; Dinema, v. Bened., [Perigonimus] ; Steenstrupia, Forbes, + Hybo- 

 codon, L. Agass., = Amphicodon, Hkl., = Diplura, Allm., + Amalthaea, 

 0. Schmidt, [Corymorpha] ; Euphysa, Forbes, [Halatractus] ; Globiceps, 

 Ay res, [Pennaria]. FAMILY 2. TIARIDAE. Genera Protiara, HkL; 

 Modeeria, Forbes ; Corynetes, M'Crady, [Halocaris] ; Amphinema, Hkl., 

 [? Perigonimus] ; Codonorchis, HkL ; Stomotoca, L. Agass. ; Pandaea, Less. ; 

 Conis, Brandt ; Tiara, Less., [Perigonimus] ; Turns, Less., [Turn's = Clavula] ; 

 Catablema, Hkl. ; Turritopsis, M'Crady, = Callitiara, Hkl. FAMILY 3. 

 MARGELIDAE. Genera Cytaeis, Esch., = Margellium, Hkl., + Cubogaster, 

 HkL, -f Dysmorphosa, Phil., + Lizzia, Forb. (pars.), [Podocoryne] ; Cytandraea, 

 HkL, [Rhizodine] ; Lizusa, Hkl. ; Lizzella, HkL ; Thamnitis, HkL ; Thamno- 

 stylus, Hkl. ; Thamnostoma, Hkl. ; Limnocea, P^ron ; Margelis, Steenstr., -H 

 Hippocrenc, Mertens, [Bougainvillea] ; Nemopsis, L. Agass. ; Rathkea, Brandt. 



