ANTHOMKIHS K KATIIKKA. 



170 



Rathkea octopunctata var. grata A. Agassiz. 

 Plate 18, fig. 5. 



Lmia grata, AGASSIZ, A., 1862, Proc. Boston Soc. Nat. Hist., vol. 9, p. 100, figs. 28, 29; 1865, North Amer. Acal., p. ihi, 

 figs. 251-258. NUTTING, 1901, Bull. U.S. Fish Commission, vol. 19, p. 376, fig. 91 . HARGITT, 1904, Bull. U.S. Bureau of 

 Fisheries, vol. 24, p. 39, plate i, fig. 4. 



\oti l.Kzia grata, FEWKES, 1881, Bull. Mus. Comp. Zix.1. at Harvard College, vol. 8, No. 8, p. 142, platf I, figs. 1-7. 



Margrllium gratum, HAFCKEL, 1879, Syst. der Mrdusen, p. 95. LEVINSEN, 1893, Vid. Mi-ddrl. Nat. Fur. Kjnbenhavn (5), Bd . 

 4, p. 145. 



Adult medusa (plate 1 8, fig. 5). Bell about 3.5 mm. in height and 5 mm. in diameter; 

 pyriform in shape, and with well-developed apical projection which is solid. The gelatinous 

 substance is thick at the apex of the bell, but thin upon the sides. There are 8 clusters of mar- 

 ginal tentacles, 4 radial and 4 interradial. The radial clusters are each composed of 5 ten- 

 tacles, while the interradial clusters contain only 3 tentacles each. The tentacles are long and 

 flexible and are usually carried curled upward. The basal bulbs are large and filled with 

 entodermal pigment-granules. The velum is well developed. There are 4 slender, straight 

 radial-canals. The peduncle of the manubrium is long and extends about two-thirds of the 

 distance from the apex of the hell-cavity to the velar opening. The gastric portion of the 

 manubrium is small, and quadratic in cross-section. There are 4 prominent lips, each of which 

 terminates in a pair of oral tentacles which end in knob-shaped clusters of nematocyst-cells. 

 There is also found a pair of knob-shaped nematocystic clusters upon the sides of each lip. 



Medusa-buds are developed in the interradii 

 upon the sides of the manubrium. The ento- 

 derm of the tentacle-bulbs and manubrium 

 is usually intense orange, but in some cases 

 the stomach is sage-green and the tentacle- 

 bulbs russet. 



Young medusa. In a medusa 1.2 mm. 

 in height there are 16 tentacles: 4 radial clus- 

 ters each consisting of 3 tentacles and 4 sim- 

 ple, interradial tentacles. The peduncle is 

 long and has the shape of the frustum of a 

 cone. The stomach is short and there are 4 

 simple lips which terminate each in a single 

 No medusa-buds are yet to be seen upon the 



FIG. 93. Rnlhken " kollikrri," = R. fasciculala, afti-r Crgrnbaur, 

 in Zeit. fiir wissen. Tool., Bd. 8. 



knob-shaped cluster of nematocyst-cells. 



manubrium. 



I he medusa-buds upon the manubrium of the adult have at first only 4 simple tentacles, 

 one at the toot of each radial-canal. At this stage there are also 4 small interradial tentacle- 

 bulbs, which lack tentacles. It is not known what condition the medusa-buds may be in at the 

 time of their liberation from the parent. 



This variety is probably an Arctic form. It appears in Newport Harbor, Rhode Island, 

 and in Massachusetts Bay during February, and disappears before June. 



It is distinguished from the European and American /,. <n tuftunitntn by its color and the 

 great length of the peduncle of the manubrium. Also the medusa-buds do not seem to make 

 their appearance until some time after the liberation of the young medusa, while in Lizziti 

 nit'jpuiictiitii they develop upon the stomach of the young medusa while it is yet attached to 

 its mother. 



Rathkea fasciculata Haeckel. 



la fasciruliita, PERON vr LJSCM'R, 1804, Ann.il. itu Mu-.. Hist. X.il.. I. 



13, p. 14^ (.an literature to 1550;. 

 Lizzia kollikeri, GFGENBAUR, 1856, Zeit. fiir wissen. Zoo]., Bd. 8, p. 225, taf. 7, fign. ^ ij. K > KM i is i \i> EMI > RS, 1862, 



Zoolog. Beitrag, p. 84, taf. 13, fig. lo. 

 Bougaini-illia kotlikrri, LEUCKART, 1856, Archiv. fijr Naturgescli., Bd. 22, p. 24, taf. 2, fig. 2. 



