22 MEDUS/E OF THE WORLD. 



They swam actively in arcs of circles, but all died early in the morning although maintained 

 in large glass dishes filled with pure sea-water. They appeared to be mature, for sperm was 

 discharged constantly from the sides of the manubrium. 



The hydroid is unknown, and possibly the medusa may not belong to the genus Pachy- 

 corJyle, though in the medusa stage it conforms with the generic character of the medusae 

 which are set free from Pachycordyle iveismanni of Naples. 



Genus AMALTH^EA Schmidt, 1854. 



Corvinorplia (hydroid), SARS, M., 1835, Beskriv og Jagttagelser, p. 7. 



Corymorpha (medusa and hydroid), STEENSTRUP, 1854, Vidensk. Meddel. Nat. For. Kjobenhavn, p. 46. 



Amahhxa (medusa), SCHMIDT, 1854, Handatlas vergl. Anatomie, p. 13. HAECKEL, 1879, Syst. der Medusen, p. 38. 



Amallhiza, ALLMAN, 1872, Monog. Tubularian Hydroids, p. 393. LOMAN, 1889, Tijdschrift, Nederland. Dierk. Vereen, Ser. 1, 



Deel. 2, p. 270. 

 Corymorpha, HARTLAUB, 1905, Zoolog. Jahrb., Abth. Syst., Suppl. 6, p. 543; 1907, Nordisches Plankton, Nr. 12, p. 75. 



GENERIC CHARACTERS OF THE FREE MEDUSA. 



Codonidae with 4 rudimentary tentacle-bulbs, 4 radial-canals, and a ring-canal. Hydroid 

 is Corymorpha, but distinguished by the character of its medusae. The majority of species 

 of Corymorpha hydroids do not give rise to free-swimming medusae. Hydroid of Arnalthtta 

 might therefore be called Amalthaa. The medusae of Amalthcra resemble those of Pennaria, 

 but the manubrium is usually longer, and extends beyond the velar opening. 



Hartlaub, 1907, includes the medusae of Steenstrufia, Euphysa, and Amalthaa in the 

 genus Corymorpha, for they all arise from identical hydroids; while the medusae differ as 

 follows: Steenstrufia, 3 short, and I long tentacle, and with an apical projection and axial 

 canal above the stomach. Euphysa, similar to Steenstrufia, but without an apical projec- 

 tion or axial canal. Amalthxa with 4 rudimentary tentacles. 



Amalthrea sarsii Allman (Medusa only). 



Corymorpha sarsii, STEENSTRUP, 1854, Vidensk. Meddel. Naturhist. For. Kjobenhavn, p. 48. BONNEVIK, 1898, Zeit.fiir wissen. 



Zool., Bd. 43, p. 476. HARTLAUR, 1907, Nordisches Plankton, Nr. 12, p. 86, fig. 82. 



Amatthtea sarsi:, ALLMAN, 1871, Monog. Tubularian Hydroids, p. 393. HAECKEL, 1879, Syst. der Medusen, p. 38. 

 ( ?) Arnaltluea amtebigera, HAFCKEL, Ibid., p. 38, taf. I, figs. 10, ll. 



It is not certain that this hydroid gives rise to free-swimming medusae, though when arti- 

 ficially set free the medusae swim about actively. 



The bell of the attached medusa-bud is elongate with a subconical basal apex and with 

 fairly thick bell-walls. It is 4 mm. high. There are usually 4 equally developed rudimentary 

 tentacles, but occasionally one of the tentacles is longer than the others. Velum well developed. 

 4 straight, slender radial-canals. Manubrium spindle-shaped. Mouth a round opening 

 studded with nematocysts. In the male the manubrium projects one-third its length beyond 

 velar opening, but in the female it is shorter and the mouth is at the level of velar opening. 

 Ova are few in number. When immature they are amoeboid, but when older they become 

 spherical and project over the surface of the gonad, attached by short pedicels. The gonad 

 encircles the entire manubrium. Manubrium straw-yellow, tentacle-bulbs light-red. Found 

 oft coast of Norway. Hydroid: Corymorpha sarsn. 



Amalthaea uvifera Schmidt. 



Amalthira uvifera, SCHMIDT, 1854, Nordisches Plankton, Nr. 12, p. 88, fig. 83. 



Corymorpha uvifera, HARTLAUB, 1907, Handatlas der vergleich. Anatomie, p. 13, taf. 9, fig. 2. 



This medusiform gonophore is not known to be set free. It is borne upon branched 

 stolons which arise from the sides of the polypite above the basal circlet of long tentacles. 

 Each stolon is tree-like and gives rise to 30 to 40 grape-like medusa-buds, so that each 

 hydroid gives rise to more than 100 buds in various stages of development. 



In the medusa-bud (when about to be set free ?) there are 4 large globular, rudimentary 

 tentacle-bulbs. The bell is higher than a hemisphere, with walls thin at apex. Manubrium 



