424 MEDUSAE OF THE WORLD. 



Liriope minima Maas. 

 Liriope minima, Maas, 1893, Ergeb. der Plankton Expedition, Bd. 2, K.c, p. 37, taf. 2, fign. 8, 10; taf. 4, fign. I, 2. 



See synoptic table of species of Liriope. 



This tropical Atlantic form appears to be the smallest known Liriope, becoming mature 

 when only 2 to 3 mm. wide. The gonads are large, double ovals on either side of the middle 

 of each radial-canal. The peduncle is 4 to 6 times as long as the bell-radius. The space 

 between the gonads is only one-fourth to one-sixth as wide as each gonad itself. This form 

 may possibly be a starved medusa which has become sexually mature. (See fig. 281.) 



Genus GERYONIA PSron and Lesueur, 1809. 



Geryonia (in part), Peron and Lesueur, 1809, Annal. du Mus. d'Hist. Nat., tome 14, p. 329. — Eschscholtz, 1829, Syst.der 



Acal., p. 86. 

 Geryonia, Lelckart, 1856, Archiv. fur Naturgesch., Jahrg. 22, p. 8.— Gegenbaur, 1856, Zeit. fur wissen. Zool., Bd. 8, p. 254. — 



Fol, 1873, Jena. Zeitschrift fiir Naturwissen., Bd. 7, p. 472. — Metschnikoff, 1886, Arbeit. Zool. Inst. Wien, Bd. 6, p. 



247; Embrvol. Studien an Medusen, Wien, pp. 23, 59, 91. — Maas, 1893, Ergeb. der Plankton Expedition, K. c, Bd. 



2, pp. 28, 31, 39. — Vanhoffen, 1902, Wissen. Ergeb. deutsch. Tiefsee Expedition, Valdivia, Bd. 3, Lfg. I, p. 85. — Bige- 



low, H. B., 1909, Mem. Museum Comp. Zool. at Harvard College, vol. 37, p. 116. 

 Leuckartia, Agassi?., L., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 364. 

 Geryones+Geryonia+ Carmaris+ Carmarina, Haeckel, 1879, Syst. der Medusen, pp. 293, 294, 296, 297. 



The type species is Geryonia proboscidalis of tropical seas first described by Forskal, 

 1775, under the name Medusa proboscidalis. This medusa is probably identical with Geryonia 

 dianea, Carmarina hastata, C. fungiformis, and C. hexaphylla of Haeckel, 1879. Carmaris 

 giltschii Haeckel is probably the same medusa with its gonads crumpled through excessive 

 contraction in the preservative fluid. 



GENERIC CHARACTERS. 



6-rayed Geryonidae with 6 radial-canals, 6 lips, 6 gonads, and 12 inclosed lithocysts. There 

 are 6 solid, primitive temporary radial, 6 hollow, permanent, secondary radial, and 6 solid, 

 interradial tentacles. Interradial centripetal canals appear to be always present. Develop- 

 ment is direct. 



Haeckel, 1879, defines four genera as follows: 



Geryones, without blind centripetal canals, with 12 tentacles; 

 Geryonia, without blind centripetal canals, with 6 tentacles; 

 Carmaris, with blind, interradial centripetal canals, with 12 tentacles; 

 Carmarina, with blind, interradial centripetal canals, with 6 tentacles. 



Metschnikoff, 1886, Maas, 1893, and Vanhoffen, 1902, have shown that blind centripetal 

 canals appear to be always present, and one can not separate genera upon the possession of 6 

 or 12 tentacles, for a study of the development shows that the first tentacles to appear upon the 

 actinula larva are 6 solid, radial ones, these followed by 6 solid, interradial, and finally by 6 

 hollow, radial tentacles. The 6 primitive, radial tentacles are soon lost and the interradial 

 tentacles may or may not be lost; so that mature medusae of one and the same species may 

 have 12 (6 hollow radial and 6 solid interradial) or only 6 radial tentacles. (See fig. 267.) 



It is evident from the above that Haeckel's new genera Geryones, Carmaris, and Carmarina, 

 represent nothing in nature and must be abolished. Haeckel lays much stress upon the 

 presence or absence of a "tongue" in the stomach in distinguishing species, but this varies 

 greatly in size and as was shown by Metschnikoff", 1886, is of no specific value. 



The development of Geryonia has been studied by Fol, 1873, and Metschnikoff, 1886. 

 It is direct, and is essentially similar to that of Liriope, excepting that the medusa is 6-rayed. 

 The entoderm is formed by delamination from the inner ends of the cells of the blastula in the 

 16-cell stage as in Liriope. 6 primary, radial tentacles and 6 interradial entodermal fusions 

 are formed instead of 4 as in Liriope. 



Geryonia is common in the Mediterranean, and has been made the subject of some inter- 

 esting physiological experiments. Krukenberg, 1880, studied the reactions to curare and 

 strychnine. Nagel, 1893, 94, found that the tentacles only are sensitive to chemical stimuli, 

 but that they do not react in lukewarm water. Sanzo, 1903, and Bethe, 1903, 08, 09, studied 

 the phenomenon of inhibition, and reaction to salts, in the rhythmical pulsation. Schneider, 

 1891, studied the histology of the nematocyst-cells. 



