338 



MEDUSA OF THE WORLD. 



Zygocanna pleuronota Haeckel. 



Mquorea pleuronota, Peron et Lesueur, 1809, Annal. du. Mus. Hist. Nat. Paris, tome 14, p. 338. 

 Mquorea (Pohxenia) pleuronota, Eschscholtz, 1829, Syst. der Acalephen, p. 119. 



Zygocanna pleuronota + Z. costata, Haeckel, 1879, Syst. der Medusen, pp. 214, 215, taf. 15, fign. 7, 8. 



Zygocanna pleuronota, Bedot, 1901, Revue Suisse de Zool., tome 9, p. 488; Ibid., 1905, tome 13, p. 153 (citation of all litera- 

 ture to 1850). 



Our knowledge of this medusa is very imperfect. Peron and Lesueur's description is 

 inadequate for modern requirements, and Haeckel states that the hell-margin of his Z. costata, 



which certainly seems to be identical with 

 Peron and Lesueur's pleuronota, is "par- 

 tially restored" in his figure. The only 

 difference between Peron and Lesueur's 

 pleuronota and Haeckel's Z. costata is 

 that Haeckel's "species" has somewhat 

 longer tentacles. The so-called disparity 

 in numbers of radial-canals, lips, and 

 tentacles is no greater than one would 

 expect to find in different individual 

 medusae of the same species in any 

 genus of the iEquoridae. 



From Haeckel's Z. "costata" Bell 

 40 mm. wide and 10 mm. high ; shield- 

 shaped and lenticular, with 32 well- 

 developed, gelatinous, radial ribs on 

 exumbrella. 16 spirally coiled tentacles, 

 longer than bell-diameter. 80 to 100 

 small lithocysts each with I concretion. 

 16 canals arise from periphery of stom- 

 ach and bifurcate, giving 32 terminal 

 branches upon which the cylindrical, 

 folded gonads are developed. Stomach cylindrical, with 16 lips. Coast of New Guinea. 

 This may be only a stage of Zygocannula diploconus. 



Peron and Lesueur's pleuronota appears to be 20 to 30 mm. wide; exumbrella with 

 40 to 50 radial ribs. Stomach cylindrical, with 16 to 20 lips. Tentacles shorter than the bell- 

 diameter. North coast of Australia. 



Zygocanna purpurea. 



Mquorea purpurea, Peron et Lesueur, 1809, Annal. Mus. Hist. Nat. Paris, tome 14, p. 337.— Milne-Edwards, 1836-49, 

 Cuvier's Regne animal, Zooph., planchc 43, fig. 3. 



Z\?pcannota purpurea, Haeckel, 1879, Syst. der Medusen, p. 215.— Bedot, 1901, Revue Suisse de Zool., tome 13, p. 153 (cita- 

 tion of literature to 1850). 



Bell flat, shield-shaped, 80 to 100 mm. wide, 10 to 16 mm. high. Tentacles short and 



very numerous. 12 bifurcated radial-canals, with 24 gonads on their outer branches. Each 



gonad forms a cluster of 5 parallel lamellae, with serrated, free, lower edges. All parts of the 



medusa are violet-purple. West coast of Australia. A modern description of this medusa is 



greatly to be desired. 



Genus ZYGOCANNULA Haeckel. 



Zygocannula, Haeckel, 1879, Syst. der Medusen, p. 216. — Bedot, 1901, Revue Suisse de Zool., tome 9, p. 488; Ibid., 1905, 

 tome 13, p. 153 (citation of literature to 1850). 



The type species is Zygocannula undulosa from the north coast of Australia. This was 

 described by Peron and Lesueur under the name Mquorea undulosa. Z. diploconus Haeckel 

 from the Straits of Sunda appears to be identical with Z. undulosa. 



GENERIC CHARACTERS. 



iEquorida? with forked or branched radial-canals, which arise at equal intervals from the 

 periphery of stomach. Stomach mounted on a gelatinous peduncle. Development unknown. 



Zygocannula is closely related to Zygocanna, but the stomach is mounted upon a peduncle, 

 whereas this is lacking in Zygocanna. It is not improbable, however, that Zygocannula is 

 only the mature condition of "Zygocanna." 



Fir.. 195. — Zygocanna "costata," after Haeckel, in Syst. der Medu 

 sen = Z. pleuronota. 



