AXTHOMKIH S.K- ( I.AIHINI.MA. (I'.l 



give rise to sucker-bearing or nematocyst-bearing branches or both. With 4 or 5 simple, oral 

 tentacles which terminate in nematocyst-knobs. There is no brood-sac above the stomach. 

 The genital products develop within the entoderm of the stomach, and when mature are 

 found in the ectoderm. The medusa is sometimes observed to be hermaphroditic. 



The type species is ClaJonctna radiatum of the coasts of Europe. According to Haeckel 

 this species is highly variable both in form and color (see Haeckel, 1879, p. 109). The two 

 American forms described by Perkins are, however, quite constant in their form, although 

 one of them is somewhat variable in color. The hydroid stock of ('.laJuni-nm belongs to the 

 tubularian genus StauriJia of Dujardin. It is well described by Allman, 1871 (Tubularian 

 Hydroids, pp. 216, 357, plate xvn), and by Perkins, 1908. 



Cladonema radiatum Dujardin. 



Cladonema radiatum, Dt'jARDiN, 1843, Compt. rend. Acad. Sci., p. 1134. 



Siauridie (hydroiil), DUJARDIN, Ibid., p. 1133. 



C.ladonema radiatum and Stauridie, DIIJARIMN, 1X43, Annal. des Sci. Nat., tome 20, p. 370; 1845, Ibid., ser. 2, tome 4. pp. 271 

 272, plate 14, fig. C. 



C.ladontma radiatum, KROHN, 1853, Muller's Archiv. fur Anat. und Physiol., p. 420, plate 13. KKFKRSTFIN i ND EHI. F, RS, 1861 . 

 Zoologische Beitrage Neapel, Messina, p. 85, taf. 13, fig. 5. VAN BENEDEN, 1866, Mem. Acad. Roy. Belgnjue, tome 36, 

 p. i 39, plate 12. HINCKS, 1868, Hist. British Hydroid Zooph., p. 62, plate 1 1 . ALLMAN, 1872, Monog. Tubul. Hydroids, 

 pp. 216, 357, plate 17, figs. l-io. HAECKEL, 1879, Syst. der Medusen, p. 109. WEI s MANN, 1883, Entstehung Sexual/ ellen, 

 bei Hydromedusen, Jena, pp. 1 19, 218, taf. 12, figs. 2-5. JICKELI, 1883, Morphol. Jahrbuch, Bd. 8, p. 602, taf. 26 (his- 

 tology). HARTLAIIB, 1887, Zool. Anzeiger, Bd. 10, p. 655, I fig.; 1907, Nordisches Plankton, Nr. 12, p. 132, fign. 123-125, 

 (list of authors; excellent description of the medusa). BEDOT, 1905, Revue Suisse de Zool., tome 13, pp. 58, 132 (refer- 

 ences to 1850). BILLARD, 1905, Bull. Museum d'Hist. Nat. Pans, tome ll, p. 500 (variations). --Mi'LLi R, 1908, Zrit. 

 fur wissen. Zool., Bd. 89, pp. 30, 73, taf. 3, figs, i, 2; taf. 4, figs. 8-1 1 . 



Bell half-egg-shaped or globular and 2 to 3 mm. wide. At Naples, Italy, the medusa 

 appears to be quite invariable, and according to Haitlaub, 1887, the manubnuin is spindle- 

 shaped and five-sided with 5 perradial oral tentacles and 5 perradial sac-like outgrowths 

 upon the sides of the stomach. Thus in the Naples medusae 5 main radial-canals, 72 apart, 

 arise from the stomach, but 3 of these bifurcate so that 8 canals, 45 apart, join the circular 

 vessel at the margin. These 5 main radial-canals are arranged as follows: 2 bifurcated 

 canals 72 apart; 2 simple, unbranched canals 144 apart; i bifurcated radial-canal mid- 

 way between the two simple canals, i. e., 72 from each. Thus in glancing around the 

 margin in the direction of the order of succession of the hour-numbers on the dial of a clock, 

 we may begin with a simple canal, then comes a bifurcated, then a simple, next a bifurcated, 

 and finally another bifurcated canal. 2 of the bifurcated canals are thus side by side and 

 the 2 simple canals are separated one from another by an interval occupied by the third 

 bifurcated canal. 



There are 8 tentacles upon the Naples medusae, one at the end of each terminal radial- 

 canal. The basal bulbs of these tentacles are heavy and swollen, and each bears an abaxial 

 ocellus, i to 3 sucker-bearing filaments arise from the inner sides of the tentacles and their 

 outer parts terminate in 4 to 6 branches which are armed with nettling warts and end in 

 knobs. 



The gonad encircles the stomach and is not confined to the sac-like protrusions, as was 

 believed to be the case by Haeckel. According to Hartlaub, the genital products originate 

 in the entoderm, but when mature are found in the ectoderm of the manubrium; yet according 

 to Weismann they originate and remain in the ectoderm. 



The medusa exhibits a successive hermaphroditism, according to Hartlaub, although 

 either sex may precede in the process. (See also Miiller, 1908.) 



The stomach, ring-canal, and tentacles are red to brown. 



This medusa is abundant oft" the Atlantic coasts of England, Holland, and V ranee, and 

 in the Mediterranean. Haeckel records a number of departures from the normal form. 

 These are probably only aberrations, but he gives specific names to each and every one of 

 them. For example, the oral tentacles and the sac-like outgrowths on the stomach may range 

 from 4 to 5; and there may be 10 simple, or 4 bifurcated radial-canals. 



There appear indeed to be many local races of this medusa, and I am inclined to believe 

 that Cladonema perkinsii and (<. nmyen of America may prove to be only varieties of C. 

 radintuin. 



