OKOKIf A.Vmn.MKDI S.K. 17 



VEILED MEDUS/E. 

 MEDUSAE CRASPEDOT^E Gegenbaur, 1856. 



Cr\ftacar/iir, ESC'HSCHOLTZ, 1829, Syst. drr Acalc'phac. 



Gymnopthalmee t FORBES, 184^, British Naked-eyed MeJuvr. 



CnispeJala, GEC-.ENBAI'R, 1856, Zeit. fiir wisscn. Zool., Bd. X, p. 217. 



Craspcdotf, HAECKEL, 1879, Syst. der Medusen. MAAS, 1X9}, Ergi-h. ilcr Plankton-Expedition] Bd. 2, K.c. 



CHARACTERS OK THK VKII.ED MEDUSJE. 



Medusae with a velum or diaphragm which partially closes the marginal opening of the 

 hell-cavity; with ectodermal gonads (i. e., the sexual products u'lifn ripe are commonly found 

 in the ectoderm). Without gastric filaments, \\irh a douhle marginal nerve-ring, one ahmi- 

 and one below the velum. Development either direct or through alternation of generations 

 from hydroids. 



Order ANTHOMEDUS^E Haeckel, 1879. 



Oceanitit (in part), GEUENBAUR, 1856, Zeit. fur wissen. Zool., Bd. 8, pp. 218, 219. 



Tubularix (in part), ACASSIZ, L., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 337. 



AnthomeJustr, HAECKEI., 1879, System der Medusen, p. 3. VANHOFFEN, 1891, Zoologischer An/eiRtr, Bd. 14, pp. 439, 442. 

 MAAS, 1905, Craspedoten Medusen der Siboga Expedition, p. 5; 1897, Mem. M. C. Z. at Harvard Coll., vol. 23, p. 9. 

 HARTLAUB, 1892, Nachrichten kgl. Gesell. \Vissenschaftcn Gottingen, p. 17; 1897, Nordisches Plankton, Nr. 12, p. 4. 

 HARGITT, 190^, Bull. U. S. Bureau of Fisheries, vol. 24, p. 29. 



CHARACTERS OF THE ANTHOMEDUSyE. 



Hvdromedusae in which the gonads are contained within the ectoderm of the manubnum. 

 There are no marginal otocysts or sensory clubs. The hydroids are of the Tubulanan order. 

 We may distinguish three families: 



(1) CodoniJif with simple tentacles, and with the gonad in the form of one or more rings 

 encircling the manubrium. No oral tentacles. 



(2) CladonemiJtr with feathered or branched marginal tentacles. Gonads ring-like, or 

 more or less separated. With or without oral tentacles. 



(3) OceaniJir with gonads confined to the interradial or adradial sides of the manuhnum 

 and separated one from another in the meridians of the principal radii. With or without 

 oral tentacles. With unhranched marginal tentacles. 



The bell in the Anthomedusae is without marginal lappets, and usually dome-shaped. 

 The tentacles arise from the bell-margin, not from the sides of the bell. The velum is simple 

 and annular, and is provided with circular muscles serving to produce the periodic con- 

 tractions of the bell. The hell-margin is simple and entire, and there are no otocysts, otohth- 

 clubs, or club-shaped sense-organs. Marginal cirri rarely present. In the young medusa the 

 exumbrella is more or less besprinkled with nematocysts, but these usually disappear or 

 become less conspicuous in the adult; although definite nematocyst tracts often persist over 

 the exumbrella, this being far more commonly seen in Anthomedusas than in other orders of 

 Hydromedusae. 



The tentacles usually arise singly from the bell-margin, and are usually simple and 

 unbranched. Ectodermal ocelli are often found upon the tentacle-bulbs, and Romanes 

 showed that in Sarsia these subserved a visual function, and that the medusa was strongly 

 attracted by rays between the red and violet. The main shafts of the tentacles are thickly 

 covered with nematocysts, which may be mounted upon filaments or converted into adhesive 

 organs, as in the Cladonemidae. The tentacle-bulbs are hollow, and connected with the 

 gastrovascular system ot the medusa. 



The radial-canals are usually simple, but in the Tiarinae they often give rise to short, 

 blindly-ending diverticula, which may be glandular in function, (ilandular swellings are 

 found in the walls of the radial-canals of L\tnn<ir,-ii iil,-\iinJri, and probably in those of /)y- 

 inorpliosa dubia and Sliikbi-ria hnltcrtita. A ring-canal is present in all genera excepting 



