TRACHYMEDUS.E — PETASIN.E. 



361 



Subfamily PETASIN^ Haeckel, 1879 (in part). 



Petasidje (in part), Haeckel, 1879, Syst. der Medusen, p. 247. — Browne, 1904, Fauna and Geog. Maldive and Laccadive 

 Archipelagoes, vol. 2, p. 735. — Maas, 1905, Craspedoten Medusen der Siboga Expedition, Monog. 10, p. 45; 1906, Fauna 

 Arctica, Bd. 4, Lfg. 3, p. 488, Jena. 



SUBFAMILY CHARACTERS. 



Trachymedusae with 4 radial-canals upon which the swollen, linear, or sac-like gonads are 

 developed. Tentacles without adhesive disks. 



This subfamily is separated from the Geryonidae by its sac-like protrusive gonads, whereas 

 the gonads of the Geryonidae are leaf-like expansions. It is distinguished from the very closely 

 allied Olindiadae by its simple tentacles, whereas the tentacles in the Olindiadae bear adhesive 

 pads. A synopsis of the genera of the Petasinae follows: 



Petasus Haeckei. sens. emend.= Pttasus+ Dipetasus+ Petatasata+ Petachnum Haeckel, 1879. Tentacles arising at equal 



intervals, not grouped in clusters. Free marginal lithocvst-clubs. 4 radial-canals. No centripetal canals. Development 



unknown. 

 Aglauropsts F. Mullf.r, 1865. Similar to Petasus, but with inclosed vesicular lithocvsts. 

 Craspedacusta Lankester, 1880 = hi mnoc odium Allman, 1880. This may be identical with Aglauropsis, but has elongate 



cavities in which the sensory-clubs are contained. 

 (?) Microhydra Potts, 1885, may be identical with Craspedacusta, but the mature medusa is unknown. 

 Gossea L. Acassiz, 1862. No centripetal canals. The tentacles are grouped into clusters and do not arise at equal intervals 



from the bell-margin. 

 Mteotias Ostrooumoff, 1896. With 4 radial-canals and numerous blindlv ending, centripetal canals. Tentacles arise at equal 



intervals from the bell-margin. Development unknown. 



Tabular Synopsis of Petasus and Allied Genera, aecording to Haeckel. 



