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Show 1896.] BRITISH HYDROIDS AND MEDUS.E. 489 ment. Owing to the ripe state of the ova in some of the specimens, I was able to distinguish the species as Thaumantias buskiana, Gosse. It is quite distinct from Phialidium temporarium and Phialidium cymbaloideum, as tbe generative organs never extend along the outer half of the radial canals, and are always round or slightly oval in shape. It may be difficult to distinguish this species in its early stages from Phialidium temporarium. I have not yet met with the two species together; the latter appears in the spring and the early part of the summer, and the former in the autumn. Gosse named this species after Busk (1849), who described a similar medusa (without giving it a specific name) taken in the Solent during the autumn of 1848. Unfortunately Busk's figures of the medusa are useless for identification. I believe that Busk took specimens of this species and also of other species which he has confused with it. Gosse was the first to give this species a description by which it may be readily identified. The following is an abstract of the description:-Umbrella when young globose, when older hemispherical or shallow campanulate, from 2 to 6 m m . in diameter, transparent and colourless. The margin of the umbrella fringed with 20-32 tentacles, very slender and extensile, with yellowish basal bulbs. A marginal vesicle between every two tentacles; sometimes two vesicles present, and occasionally a vesicle has two otoliths. Ovaries small, oval, on the radial canals, containing globular ova in various degrees of development. Stomach small and quadrangular. Taken at Hfracombe in the autumn. The Plymouth specimens agree with the description given by Gosse. The species closely resembles Phialidium variabile (Claus), from the Mediterranean. I prefer to keep them separate for the present until the hydroid forms have been identified. It also closely resembles the figure given by Forbes of Thaumantias thompsoni, which was taken by Forbes on the coast of Cornwall and in Boundstone Bay on the west coast of Ireland. Bohm (1878) has described the medusa under the name of Clytia johnstoni from Heligoland. Hartlaub (1894) has recorded Phialidium variabile (Claus) (not Haeckel) from Heligoland. PHIALIDIUM TEMPORARIUM, Browne. (Plate XVII. figs. 4,5, 6.) I find it is necessary to give a specific name to one of the commonest medusae on our coasts. It is probable that Forbes described this species under the name of Thaumantias hemisphcerica, but as Haeckel has taken Thaumantias hemisphcerica as the type of the genus Thaumantias, and many other naturalists have placed the species upon their lists, it is necessary to retain it. I have already described some specimens of this species under the name of Phialidium variabile, Haeckel, in the ' Eeport on tbe Isle of Man Medusae'; but I have since discovered that Phialidium |
