12f) MEDUSA OF THE WOULD. 



Turris vesicaria A. Agassiz. 



Plate ll, figs. 2 and 3; plate 13, fig. 7. 



Turris vesicaria, AC.ASSIZ, A., 1862, Proc. Boston Soc. Nat. Hist., vol. 9, p. 97; 1865, North Amer. Acal., p. 164, figs. 261-268. 



NUTTING, 1901, Bull. U. S. Fish Commission for 1899, vol. 19, p. 375, fig. 86 (abnormal medusa). 



C.nlablema vesicarium, HAECKF.L, 1879, Syst.der Medusen, p. 64. GRONBERG, 1898,200!. Jahrb., Abth. Syst., Bd. n, p. 461. 

 Turris efitcopalit, FEWKES, 1881, Bull. Mus. Comp. Zool. at Harvard College, vol. 8, p. 147, plate 3, figs. 1-6. 

 Turris vesicaria, and T. efiscofalis, HARC.ITT, 1904, Bull. U. S. Bureau of Fisheries, vol. 24, p. 36, 2 figs. 

 Catahlema I'tsicarium (young medusa), MAAS, 1904, Result. Camp. Sci. Prince de Monaco, fasc. 28, p. 12, planches I, 2. 



Adult medusa (plate 13, fig. 7). Bell about 25 mm. in height and 12 mm. in diameter. 

 There is a large, solid, apical projection which varies greatly in shape, being globular in some 

 individuals, while in others it is cylindrical or conical. Its upper end is often seen to terminate 

 in a small button-shaped projection. The side walls of the bell are quite thin and flexible. 

 There are 16 well-developed tentacles, the basal bulbs of which are quite large and are 

 flattened in a radial direction, so that the tentacle appears to arise from the side of the bell 

 slightly above the bell-margin. These well-developed tentacles are very flexible, and when 

 ejctended are about 2 to 4 times as long as the bell-height. These basal bulbs are hollow and 

 bear each an abaxial ocellus. In addition to these long tentacles there are 48 very short, rudi- 

 mentary tentacles, which arise from the bell-margin at a slightly lower level than the long ten- 

 tacles. There are 3 of these rudimentary tentacles between each successive pair of long 

 tentacles. There is a single dark-red ocellus upon the outer side of each and every tentacle- 

 bulb, 64 in all. The velum is narrow. There are 4 broad, flat radial-tubes and a broad, 

 circular canal, all of which display jagged edges. The 4 radial-canals enter the stomach by 4 

 wide, funnel-like openings. The manubrium is large and urn-shaped and there is no peduncle. 

 The mouth is surrounded by 4 prominent, crenulated lips. The gonads occupy 4 interradially 

 situated, longitudinal regions upon the walls of the stomach. Each gonad consists ot a pair 

 of swollen, papilliform, adradial, ectodermal ridges, the outer surfaces of which are thrown 

 into complex, but mainly transverse, folds and corrugations. The color of the manubrium and 

 tentacle-bulbs is cinnamon-brown, the gonads being of a somewhat darker shade. The 

 ocelli upon the tentacle-bulbs are dark-red. 



y otnig medusa (plate 12, fig. 2). In the youngest medusa observed the bell is about 2 mm. 

 in height. The walls are thin, and there is a short, conical, apical projection. There are only 

 4 well-developed tentacles, one at the base of each of the radial-canals. These tentacles have 

 large conical basal bulbs which are hollow. The axes of the tentacle-bulbs are at a slight dis- 

 tance above the bell-margin. In addition to the 4 well-developed, radial tentacles, there are 4 

 intermediate interradial tentacles which arise from the bell-margin at a slightly lower level than 

 the radial tentacles. The 4 radial-canals are broad and their edges are jagged. The manubrium 

 is large and quadratic in cross-section. The lips are simple. 



In a medusa 3 mm. in height (plate 12, fig. 3), there were 8 well-developed and 8 immature 

 tentacles. The apical projection was large and miter-shaped, and the lips had folded, notched 

 margins. 



This medusa is probably an Arctic species. It has been found but rarely south of Cape 

 Cod, and then only in May and June. It is abundant, however, in the harbor of Eastport, 

 Maine, in August, and ample opportunities for observing its growth were afforded. 



The medusa is remarkable for its voracity and will devour Nanomia cara with great 

 avidity. It is a common thing to observe the medusa in the act of devouring one of these large 

 Siphonophores which may be many times its own size. Maas, 1904, records this medusa off" 

 Bear Island, between Norway and Spitzbergen, so that its distribution is probably circum- 

 polar. Grcinberg records it as being rare in August off" the coasts of Greenland and Spitz- 

 bergen. 



Turris superba (a variety of T. pileata). 



Plate 27, fig. 8; plate 28, figs. 3 and 4. 



Tiara superba, MAYER, 1900, Bull. Mus. Comp. Zool. at Harvard College, vol. 37, p. 34, plate 16, fig. 39; Memoirs Nat. 

 Sci. Museum Brooklyn Inst. Arts and Sci., vol. I, No. I, p. 8, plate 2, fig. 1 1. 



Bell 5 to 7 mm. high and with a well-developed apical projection. There are 4 long, 

 hollow and 12 small, solid, rudimentary tentacles. The long tentacles are slender, with taper- 

 ing basal bulbs. There is an ectodermal ocellus upon the outer side of the tentacle-bulb of 



