460 MEDUSA OF THE WORLD. 



Velum at the bell-margin similar in structure to velum of Hydromedusae. Subumbrella 

 cavity about half as deep as bell-height; the manubrium is a short, simple tube. The central 

 stomach gives rise to an apical canal which ends blindly immediately under the apical sense- 

 organ, and also to 2 lateral branches which lead to the bases of the 2 tentacles. There is no 

 peripheral canal-system. The muscles of the subumbrella are poorly developed and the 

 animal swims mainly by contractions of its powerful velum and by movements of its tentacles. 



The tentacles are red and the bristle-bearing ring around the opening of the sensory 

 canal at the bell-apex is orange. All other parts are colorless. No gonads were observed. 



Three specimens were found by Dawydoff, swimming near the surface of the sea off 

 Saparcea Island near Amboina, in July, 1902. 



This Ccelenterate resembles the Hydromedusae in the general shape of the bell and in the 

 structure of the velum and manubrium. The presence of true nematocysts places it among 

 the medusae rather than among Ctenophorae and the histology of the gelatinous substance of 

 the bell resembles that of Hydromedusx. On the other hand, it is the only known Hydro- 

 medusa which has an apical sense-organ when adult. It resembles the Ctenophorae in having 

 2 diametrically opposite tentacles, which may be partially retracted into special sheaths. 

 Moreover, the cores of these tentacles are not composed of entodermal cells, but of solid, 

 gelatinous substance (mesoglcea) continuous with that of the bell-walls. The stomach gives 

 rise to an axial and 2 lateral diverticula as in Ctenophorae. 



There are, however, no colloblasts, as in Ctenophorae. Moreover, in Ctenophorae we 

 find an ectodermal pharynx, or stomodeum, and this is absent in Hydroctena as are also 

 ciliated combs, so characteristic of Ctenophorae. Indeed, were it not for its apical sense-organ 

 which bears only a superficial resemblance to the apical sense-organ of Ctenophorae, Hydro- 

 ctena would be unquestionably classed among the Hydromedusae. Its resemblances to the 

 Ctenophorae appear to me to be parallelisms and not due to genetic relationship to Ctenophorae. 

 I am inclined to regard Hydroctena as a highly specialized Narcomedusa. Maas believes 

 Hydroctena to be a typical Narcomedusa, apparently Solmundella. Schneider on the other 

 hand appears equally certain that it is a Ctenophore. "Where doctors disagree 'tis folly to 

 be wise," and we must await the observation of future students. 



Woltereck, 1905, finds that in the larval Solmundella and in the actinula larva of Tubularia 

 there is an apical pole-plate, consisting of ciliated ectodermal cells. In Tubularia this pole- 

 plate is surrounded by a ring-like ridge of ectoderm so that the ciliated cells become somewhat 

 sunken beneath the general level of the apex. In view of these observations, the apical sense- 

 organ of Hydroctena loses its extreme isolation and it becomes more than ever probable that 

 Hydroctena is merely a highly-specialized Narcomedusa related to Solmundella. 



Genus CUNOCTANTHA Haeckel, 1879, sens, emend. 



Cunina (in part), Eschscholtz, 1829, Syst. der Acalephen, p. 116.— Lesson, 1843, Zooph. Acalephes, p. 301.— Gegenbair, 



1856, Zeit. fiir wissen. Zool., Bd. 8, p. 259. 

 Cunina, McCrady, 1857, Gymn. Charleston Harbor, p. 108. 

 Fovtolia, Acassiz, A., 1865, North Amer. Acal., p. 51. 



Cunina, Uljanin, 1876, M3B'tcTiji 06mecTBa JJ.io6aTe.ieii EcTecToaHama, etc., tome 24,Moskau. 

 Cunoctantha, Haeckel, 1879, Syst. der Memsen, p. 316. — Metschnikoff, 1881, Zeit. fiir wissen. Zool., Bd. 36, p. 437. — 



Brooks, 1886, Mem. Boston Soc. Nat. Hist., vol. 3, p. 361. — Metschnikoff, 1886, Arbeit. Zool. Inst. Wien, Bd. 5, p. 



252. — H. V. Wilson, 1887, Studies Biol. Lab. Johns Hopkins Univ., vol. 4, p. 95. 

 Gastrodcs (degenerate parasite), Korotneff, 1888, Zeit. fiir wissen. Zool., Bd. 48, p. 640. 

 Cunoctanlha, Korotneff, 1891, Zeit. fur wissen. Zool., Bd. 51, p. 618. — Maas, 1892, Zool. Jahrb., Abth. Anat., Bd. 5, p. 271, 



taf. 21, 22, 26 fign. (development of medusa-buds upon the larva). 

 Cunina, Maas, 1893, Ergeb. der Plankton Expedition, Bd. 2, K.c, p. 53. 

 Cunociantha, Maas, 1905, Craspedoten Medusen der Siboga Expedition, Monog. 10, p. 66. — Woltereck, 1905, Verhandl. 



Deutsch. Zool. Gesell., 15 Jahresvers., p. 1 17.— Bic.elow, H. B., 1909, Mem. Comp. Zool. at Harvard College, vol. 



37, P- 5'- 



The type species is Cunoctantha octonaria, described by McCrady, 1857, from Charleston 

 Harbor, South Carolina, under the name Cunina octonaria. 



Haeckel established the genus Cunoctantha and describes C. discoidalis as the first species. 

 This appears, however, to be a young stage of some Cunina, and McCrady's previously 

 described C. octonaria should serve as the type of the genus. 



