Abstract
LONDON Linnean Society, November 19.—Prof. Moseley, F.R.S., in the chair.—Mr. A. D. Michael exhibited and described the remarkable nymphal stage of Tegeocranus cepheiformis, a species of the Orihatidse, which he lately discovered for the first time in England. He has furthermore succeeded in tracing the whole life-history of this animal. The creature in its nymphal stage is exceedingly strange and beautiful. It carries on its back as concentric shields the dorsal portions of all its cast-skins, and these are bordered by projections each bearing a rose-leaf-like cuticular process of transparent membrane with chitinous nervures. The drawing of the nymph was first sent to Mr. Michael, two years ago, by Herr Pappe, of Bremen.—Mr. C. Stewart demonstrated, under the microscope, the stridnlating apparatus of a species of Sphærotherium, differing in some respects from that described by Mr. Bourne (infra).—Dr. J. Murie exhibited and made remarks on the caudal end of the spine of a haddock with an arched deformity, recalling what is recorded of the so-called hump-backed cod (Morrhua macrocephala).—Mr. G. J. Fookes called attention to some twin-apples, of teratological interest. These were grown at Shepherd's Bush, upon a tree eighty years old, which last year was nearly barren, but this year produced abundantly, many of the fruits being good examples of syncarpy. —Prof. P. M. Duncan read a paper on the perignathic girdle of the Echinoidea. The author maintained that as the structures which give attachment to the muscles that protrude and retract the jaws of the Echinoidea (which are parts of the test surrounding the peristome within) are not homologous in all the families of the group, therefore it is unadvisable to retain the old name of “auricles.” He suggests to substitute the term “perignathic girdle.” The girdle consists of processes usually united above (though occasionally disconnected), and of “ridges which connect the processes on the side remote from the ambulacra. The ridges are modifications of the inter-radial plates, the processes developments from the ambulacral plates. In the Cidaridæ, the muscular attachments are all on disconnected ridges, and there are no processes. In the Temnopleuridæ, Echinidæ, Echinometridæ, and Diadematidæ, the retractor muscles are attached to “processes” which are growths of the poriferous portions of the ambulacral plates; and the protractor muscles and ligament of the radiales are attached to the ridge which is developed on the inter-radial plates, and is united by suture to the base of the “process.” In the Clypeastridæ there are disconnected growths which carry the jaws and have slight muscular attachments. In Clypeaster there are ten processes, each arising from an ambulacral plate; and there are no inter-radial structures like ridges. In Laganum there are five growths, each arising from a first inter-radial plate; hence these are the homologues of ridges. The Clypeastridæ may thus be divided into two groups, on account of the presence of processes in one, and of the homologues of ridges in the other.—Prof. Moseley communicated a paper on the anatomy of Sphæroherium by Mr. G. C. Bourne. The author mentioned that while the general exterior features and specific distinctions of the genus had been amply discussed, the internal structures had hitherto received scant attention. Among other anatomical peculiarities he describes a well-defined stridulating organ in the male. This consists of a prominent bolster-shaped swelling on the postero-external edge of the second joint of the second pair of copulatory appendages. The swelling occupies the entire margin of the joint, and shows a number of chitinous cross ridges and furrows. On the opposite interior surface of the last tergite are chitinous points. The former rasp-like organ of the second accessory appendages when rubbed rapidly against the latter produce a shrill note resembllng that emitted by the house cricket. A true auditory organ exists in the antennary fossa beneath the eye. The tracheal system is unlike the majority of that of the Diplopoda, rather resembling that of Chilopoda and Insecta, though differing in the branched spiral filament not taking origin directly from the stigmata themselves. It appears that the tracheæ of Sphærotherium are a transition from those of the Julus type to those of the Scolopendra type. It would thus seem that the character of the trache, the curved alimentary tract, the numerous chitinous pieces composing each segment, and the presence of a special hearing organ on the head, mark off the family Glomeridre (to which Sphærotherium belongs) very sharply from the other families of the Diplopoda.—Prof. Moseley afterwards read extracts of letters from Mr. G. C. Bourne, who is now in the Chagos Archipelago, and from Mr. Sydney Hickson in the Celebes (Oxford graduates), and now investigating the natural history of the regions in question.—There followed a paper, contributions to South African botany, Orchideæ, part 2, by Mr. H. Bolus, with additional notes by Mr. N. E. Brown.
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Societies and Academies . Nature 33, 119–120 (1885). https://doi.org/10.1038/033119c0
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DOI: https://doi.org/10.1038/033119c0