LEPTO MEDUSAE TIMA. 



317 



Tima formosa L. Agassiz. 

 Plate 41, figs. 1-3. 



Tima formosa, Agassiz, L., 1862, Cont. Nat. Hist. U. S., vol. 4, p. 362.— Agassiz, A., 1865, North Amer. Acal., p. 1 13, figs. 164- 

 172.— Verrill, 1873, Report Commiss. Fish and Fisheries for 1871-72, p. 449.— Haeckel, 1879, Syst. der Medusen, 

 p. 205.— Fewkes, 1 88 1, Bull. Mus.Comp.Zool. at Harvard College, vol.8, No. 8, p. 157, plate 6, figs. 1, 4-6.— Nutting, 

 1 901, Bull. U.S. Fish Commiss. for 1899, vol. 19, p. 379, fig. 96.— Hargitt, 1904, Bull. U. S. Bureau of Fisheries, vol. 24, 

 p. 47, plate 4, fig. 2. 



(?) Tima bairdii (young medusa), Forbes, 1848, British Naked-eyed Medusa;, p. 37, plate 5, figs. 1-16. 



Adult medusa (plate 41, fig. l). — This is one of the largest hydromedusae found upon the 

 coast of the United States. The bell is about 100 mm. in diameter and 65 mm. in height. 

 The gelatinous substance is thick at the apex, but gradually becomes thinner toward margin 

 of bell. There are normally 32 well-developed tentacles; 8 of these are about as long as the 

 bell-diameter, 8 others about half as long, and the 16 others about one-quarter as long as bell- 

 diameter. The basal bulbs of the tentacles are long, fleshy, and ribbon-like, with a strand 

 of longitudinal muscle fibers on their inner (velar) sides and their distal ends are usually 



Fig. 176.— Hydroid and medusa of " Campanulina repens," after Hincks, in British 

 Hydroid Zoophytes. This may be the hydroid of Tima or Eirent. 



turned upward toward the bell-margin (plate 41, fig. 2). The main shaft of the tentacle is long 

 and contractile and hangs downward from the turned-up end of the basal bulb. The basal 

 bulbs and tentacle-shafts are hollow. There are no lateral cirri at the sides of the tentacles, 

 but there are 3 very small rudimentary protuberances upon the bell-margin between each 

 successive pair of tentacles. Thus in all there are 96 of these small protuberances which 

 never increase in size and are evidently rudimentary tentacles. There are 128 lithocysts alter- 

 nating in position with the 128 functional and rudimentary tentacles. Each lithocyst contains 

 15 to 20 angular concretions, arranged in a semicircle near the periphery of the cavity. Velum 

 well developed. There are 4 straight, narrow, radial tubes. A wide, conical peduncle pro- 

 jects considerably beyond the velar opening. The stomach is quadrangular in cross-section 

 and provided with 4 long, folded, curtain-like lips. The 4 gonads are situated upon nearly 

 the whole length of the 4 radial-canals. They are longer than the canals upon which they lie, 

 and are, therefore, deflected from side to side in sinusoidal curves. In the female the eggs are 

 large and prominent. 



Gonads and stomach opaque and cream-colored; tentacles delicate creamy-pink. All 

 other parts of the medusa are as transparent as glass. 



