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Show 540 MR. J. T. CUNNINGHAM ON THE [June 1 7, 7. On Secondary Sexual Characters in the Genus Arnoglossus. By J. T. CUNNINGHAM, M.A., F.R.S.E., Naturalist to the Marine Biological Association. [Received June 10, 1890.] I. ARNOGLOSSUS LATERNA, Giinther. The history of the species Arnoglossus lophotes, Giinther, has been quite recently reviewed by Dr. A. Giinther in the Proceedings of this JSociety1. I need not therefore repeat it here in detail. But it is necessary to mention that Couch in his ' History of British Fishes ' (1864) recorded that he had examined a dried skin of the form in question at the house of Lieutenant Spence, R.N., at Plymouth, this specimen having been taken, we are told, in the neighbourhood of that port. The only entire specimens examined by Dr. Giinther were one trawled by Prof. Moseley in 1882 near Lundy Island, aud one sent from Palermo. Until December 1889 I had never met with any specimens in the course of m y observations at Plymouth which exhibited the characters ascribed to A. lophotes. At the beginning of that month I collected specimens of A. laterna in order to make an attentive examination of its characters. I asked a man employed on the fish-quay to bring me a number of full-grown specimens of the ' Scald-fish,' as the species is called at Plymouth, from the trawling-smacks which came in from the fishing-grounds. Among the specimens he brought me I was much surprised as well as pleased to find a number which presented the peculiarities of A. lophotes. In fact, whenever the man brought a number of Scald-fish from the trawl refuse, there were more A. lophotes than A. laterna among them. The specimens were obtained at all parts of the trawling-grounds off Plymouth, that is from 3 to 15 or 20 miles off the south coast of Devon and East Cornwall. On subsequent excursions in trawlers, both in the neighbourhood of Plymouth, off Mounts Bay, and in the Bristol Channel, I found that the lophotes form always occurred along with A. laterna and was more abundant than the latter. I of course made a careful examination of the specimens obtained, and was for some time puzzled by the close similarity between the two forms in the majority of their characters. I found, too, on examining smaller and therefore younger specimens that none of them exhibited the elongation of the anterior dorsal fin-rays which characterizes A. lophotes, but that this character was confined to specimens above a certain size. I began to think that if the two forms were really distinct species, they were more exactly similar in the majority of their characters than two distinct species usually are. Then it occurred to me to ascertain the sex of every specimen ; and I found that specimens of A. lophotes were invariably males, and adult specimens of A. laterna invariably females. Having found 1 " A Contribution to our Knowledge of British Pleuronectida.." P. Z. S. 1890, p. 40. |