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Show 490 MR. E. T. BROWNE O N [Mar. 17 variabile, Haeckel, consists of several distinct species, one being Phialidium (Eucope) variabile (Claus), a species probably identical with Phialidium buskianum (Gosse). Bohm (1878) has given Campanidina acuminata as the name of this species, which he has described and figured in the adult stage, taken off Heligoland. Bohm has not reared the medusa from the hydroid, and does not show that the young medusa from the hydroid Campanulina acuminata develops into the medusa which be has described under the same name in the adult condition. N o doubt the young medusae from the hydroid Campanulina acuminata do develop into one of the species belonging to the genus Phialidium. For this reason I have not used Bohm's specific name of the adult medusa, as it may not belong to the hydroid Campanulina acuminata. I give here a description of the various stages of Phialidium temporarium:- 1st Stage. Four tentacles. (Plate XVII. fig. 4.)-The earliest free-swimming stage, which I have seen, was taken at Valencia in M a y 1895. Umbrella bell-shaped, about § m m . in length and width. Four perradial tentacles and four interradial tentacle-bulbs. Eight marginal vesicles with a single otolith in each. Tentacle-bulbs and the basal bulbs of tbe tentacles yellowish brown. Stomach short; mouth with four short lips. In one specimen the apical stalk, or the prolongation of the stomach into the substance of the umbrella, was still present, indicating that the medusa had not long been liberated from its hydroid. The generative organs form a minute round or oval swelling, one on each radial canal, about halfway down. 2nd Stage. Eight tentacles.-The interradial bulbs belonging to the first stage develop tentacles, and a little later some of the adradial bulbs begin to appear. It may be sometimes difficult to distinguish at this stage this species from Phialidium cymbaloideum, as both possess eight marginal vesicles, but in the latter species I have always seen at least two otoliths in all the vesicles. In Phialidium temporarium occasionally two otoliths may be present in one vesicle, but never in all the vesicles. 3rd Stage. Sixteen tantacles and 16 or more marginal vesicles.- The adradial tentacles appear in no definite order, so that one quadrant sometimes contains more tentacles than another. The marginal vesicles also increase in number, one is always present between every two tentacles, occasionally two may be present. The umbrella grows faster in width than in length, being about 6 to 7 m m . in wddth and 4 to 5 m m . in length. The generative organs grow downward towards the margin and become oval-shaped. The colour of the generative organs shows slight variations, usually yellowish brown, occasionally reddish brown. Adult Stage. (Plate XVII. figs. 5 & 6.)-The largest specimen which I have measured was 21 m m . in width and 11 m m . in length, with 38 tentacles. Two or three marginal vesicles between every |
