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Show 832 MR. E. T. BROWNE ON BRITISH MEDUS.E. [NOV. 16, vesicle shows considerable variation ; they are usually placed in nearly a straight line, but often form a semicircle, and are occasionally arranged in opposite pairs, as described by Haeckel in Polycanna fungina. Literature.-A search into the literature relating to the genera JEquorea and Polycanna led m e to a paper published by Forbes in the 'Proceedings' of this Society for 1851, " O n a Species of JEquorea inhabiting the British Seas," taken in the Outer Hebrides. The medusae taken at Valencia closely correspond to the description and figures given by Forbes, who, after a careful investigation of the early literature, decided that bis specimens belonged to the species known as JEquorea forskalea (Peron). I have examined the earlier references relating to this kind of medusa, and believe that it is not possible to recognize wdth certainty the species described by the early naturalists. Haeckel (1879) brings together all the early references relating to JEquorea forskalea (Peron), but has omitted Forbes's JEquorea. Claus (1881) describes specimens of JEquorea forskalea taken at Trieste, and criticizes Haeckel's classification of the iEquoreidae. Hartlaub (1894) describes specimens from Heligoland under the name of JEquorea forskalea (Peron). Our present knowledge of this interesting group is certainly not in a very satisfactory condition. Probably, when more is known about them, there will be a considerable reduction in the number of species and Claus's views confirmed. For the present I think it is best to leave tbe Valencia specimens under the name of Polycanna forskalea (Forbes). A LEPTOMEDUSA (gen. ? sp.?). (Plate XLIX. figs. 3, 3a.) This is an interesting little medusa which I have found only in Valencia Harbour : a single specimen in M a y 1895, and three in August 1896. Description.-Umbrella egg-shaped, about 1 m m . in length and width. Stomach and mouth absent. Four radial canals. Four browuish tentacle-bulbs, without tentacles. Eight marginal vesicles, each with a single otolith. About halfway down each radial canal there are three pairs of dark brownish, irregular lobes, which project into the umbrella-cavity. Velum very broad. The absence of the stomach and mouth and of the tentacles, and the presence of lobes on the radial canals, were noticed in all the specimens. Gonads probably develop upon the lobes of the canals, but none were visible in these specimens. I do not believe that this medusa has been described, and refrain from giving it a name. Most likely it comes from a Calyptoblastic hydroid which has probably already received a name; if so, let it receive its hydroid namel. 1 Since this paper was read Dr. C. Hartlaub has published a description of this medusa from examples taken off Heligoland. It is named Agastra mira (sp. et gen. nov.). (Arbeiten biol. Anstalt Helgoland, 1897, Bd. ii. p. 504.) |
