LEPTOMEDU8.*: MELICERT1 M. L'OT 



Genus MELICERTUM Oken i sensu Ehrenberg and Agassizi. 



Mrliirria, preoccupied by SCHKANK, 1805, for Rotifers. OKEN, 1815, Lehrbuch dor Naturgesch., Bd. i, Register p. 4. |'. 1:5. 

 PKRON rt Lt si' n'R, 1809, Ann. du Mus. Hist. Nat. Paris, tome 14, p. 352. LESSON, 1843, Hist.Zooph. Acal., p. 324. 



Mflirerlum, OKF.N, 1835, Allgemeinc Naturgesch. fiir alle Stande, Bd. 5, p. 216. ESCHSCHOLTZ, 1829, Syst. der Acalephrn, 

 p. 105. EHRF.NBERG, 1837, Abhandl. Akad., 1835, Berlin, p. 255. AGASSIZ, L., 1862, Cont. Nat. Hist. I'. S., vol. 4, 

 pp. 349, 352. AGASSIZ, A., 1862, Proc. Boston Soc. Nat. Hist., vol. 9, p. 96; 1865, North Ainer. Acal.. p. 130. 

 MAAS, 1897, Mem. Mus. Comp. Zool. at Harvard College, vol. 23, p. 19.-- I.I\KO, 1904,200]. Anzeigcr, Bd. 28, p. j|8. 



CampiineUa, Mourn, 1857, Beskriv af Gronland, p. 95. 



Melicertella -t- Melirertum, HAF.CKEL, 1879, Syst. der Medusen, pp. 134. 136. 



Meliccrtidititn, BROWNK, 1901;, Proc. Royal Soc. Edinburgh, vol. 25, p. 764. 



The name Melicerta appears, inadequately defined, in Oken's Lehrbuch, 1X15, on page 

 iv ot the index and page 125 ot the text. The same medusa is apparently described by Oken. 

 1X35, under the name ot Melicertum campanula from Greenland. In Oken's Melicertum 

 there are but 4 radial-canalsf ?) and the stomach is tubular and quadratic in cross-section 

 with 4 short lips. The marginal tentacles are of unequal length. It seems impossible to 

 determine whether the medusa described by Oken is or is not the young ot the M. campanula 

 of Agassi/,. The name "Melicerta" is preoccupied, and "Melicertum" would have been 

 hopelessly lost through inadequate definition had it not been clearly defined by A. and L. 

 Agassiz, 1862, 1865. 



(JKNERIC CHARACTERS. 



Thaumantiadae with 8 gonads upon the 8 radial-canals. 8 or more tentacles. Without 

 marginal sense-clubs or cirri. With or without a gastric peduncle. The hydroid is .I/,/;, ,-rtnm. 



Melicertum as here defined is equivalent to M clici-ituni \ Mrli, , -it, II, i of Haeckel, 

 Hartlaub, 1894, and Browne, 11)05, have discovered that Oicniim 'n In, >n tutu Sars, 1835, 

 lacks marginal cirri and has all of the characters of Agassi/.'s Mrlicfrtum. Haeckel labored 

 under the false impression that this medusa had marginal clubs and he therefore established 

 his new genus "MelicertiJium" especially for this species. Browne would therefore amend 

 M elicertidium and define it in the sense of the older genus Melicertum, doing away with Melt- 

 cerium. Bur it appears that Ehrenberg, 1837, placed Sars's species in the genus M<-ln<-rtu>n, 

 and I think it should remain there and be considered a cotype of that genus. 



Melicertum campanula Oken(?i, Agassiz. 



Plate 23, figs. 4, 5; plate 24 fig. 5. 



(?)Mrliccrtum ramfanula, OKEN, 1835, Allgemeinr Naturg. fiir Alle Stande, Bd. c, p. 226. 



Mrliccrlum campanula, AGASSIZ, L., 1862, Cont. Nat. Hist. I'. S., vol. 4, pp. 349, 352 AI.ASM/,, A., |S(>;, I'm. . Huston Sen 

 Nat. Hist., vol. 9, p. 96, figs. 1 8, 19; 1865, North Amer. Aca!., p. 130, figs. 202-214. HAM KM., 1879, Svst. drr Mr, I 

 p. 137. Nt TTINI., 1901, Bull. U. S. Fish Commission for 1899, p. 382, fig. 104. HARI.IT r 1904. Bull. I . S. Bureau of 

 1'isherirs, vol. 24, p. 44. I.INKO, 1904, Zool. An/eiger, Bd. 28, p. 2|8. 



Mftitertidium {(ittipaiiula, BROWNK, 1905, Proc. Royal Soc. Edinburgh, vol. 2s", p. 766. 



Adult infiiusa (plate 23, fig. 5). Bell pyntorm in outline and about 25 mm. in height and 

 25 mm. in diameter. The gelatinous substance is quite thick, especially at the aboral pole. 

 There are about 70 long, flexible tentacles with hollow, conical, basal bulbs. The tentacles 

 arise from the hell-margin and are all longer than the bell-height. There are no marginal 

 cirri or lithocysts between the tentacles, nor any ocelli. The velum is well-developed. There 

 are 8 simple, straight, quite broad radial tubes. The manubnum is wide and shallow and 

 does not extend quite half the distance from the inner apex ot the bell-cavity to the velar open- 

 ing. There are 8 simple, recurved lips. The 8 gonads occupy the entire lengths of the S 

 radial-canals. These are longer than the canals upon which they lie and are reflected from one 

 side to the other of the radial-canals in sinusoidal curves. The entoderm of the manubiium, 

 gonads, and tentacle-bulbs is ocher-yellow, and the bell often displays a taint yellow tinge. 



H \drold and \ouno medusa. The eggs are cast into the water and develop into pear- 

 shaped planulae. The planulae are ciliated and swim about near the bottom of the aquarium. 

 They soon attach themselves by the blunt (foremost) end. and the narrow ((undermost) end 

 then develops into a long, narrow trunk, which becomes the mam stem of the hydroid. The 

 distal extremity of the stem expands and forms the first polvpite. The polypites are long. 

 cylindrical, and protected by a small, funnel-shaped hydrotheca at their proximal ends. 



