memberless (member les)

[ vided. minal part of a hem i elytrum; the membrane of the fore wing of a hemipter. See cut under cla vus.-3. A skin prepared for being written on. They consist of three bundles, containing in all 549 skins or membranes. Of these membranes, the greater part are vellum and parchment. English Gilds (E. E. T. S.), Int., p. xliv. membrane, a membrane dividing the muscle-fiber transversely, supposed to be indicated by the intermediate line in the light disk of striated muscle-fiber. Also called Do bie's line, Dobie's stripe. - Limiting membrane of the retina, external and internal, the outer and inner boundaries of the Abers of Müller, presenting the appearance of continuous membranes, the outer lying between the outer nuclear layer and the layer of rods and cones, and the inner being next to the hyaloid membrane. - Membrane of Bruch, a structurele or finely fibrillated transparent membrane, lying between the cho rio cap ill aris and the pigmented layer of the retina. - Membrane of Corti. Same as tectorial membrane. Membrane of Demours, or membrane of Descemet, a transparent, gla y lamina, covering posteriorly the proper ti ue of the cornea, itself lined with a single layer of epithelioid cells. Also called posterior elastic lamina. Membrane of Henle. Same as Henlean membrane. Membrane of Rei ner, the membrane which separates the scala vestibuli of the cochlea from the cochlear canal or scala media. It extends obliquely from the spiral lamina to the outer wall of the cochlea. It is a very delicate layer of connective ti ue continuous with the periosteum of the upper surface of the bony lamina, and lined with pavement epithelium on its lower side. - Mucous membrane, the general lining membrane of the alimentary canal and its annexes, including the respiratory and urogenital pa ages. It is one of the most extensive and the most complex of the membranes of the body, varying greatly in character in different cases, and in different parts of its own extent, and may include various special glandular structures, as mucous crypts, follicles, etc., as well as the appropriate nerves, blood-ve els, and lymphatics. Mucous membrane consists e entially of a basement membrane (see basement ), which separates a free epithelial from a fibrovascular attached layer. The epithelium is a layer of cells of various kinds, as spheroidal, columnar, ciliated, etc.; the fibrovascular layer consists of connective ti ue with ve els, lymphatics, nerves, and often muscular fibers. Embedded in this membrane may be also the glandular structures above mentioned; and the surface is often thrown up into various ridges, villi, and papillæ. The structure is e entially a secreting one, giving rise to mucous as well as to various other special secretions. At the openings of the body the mucous membrane is directly continuous with the skin. The conjunctiva of the eye is also a mucous membrane.-Nasmyth's membrane, the cuticula dent is, or cuticle of a tooth; the epithelial investment of the enamel of a young tooth, which persists for a while and then wears off. Nictitating membrane, the winking membrane or winker; the third eyelid. It is very highly developed in some animals, as birds, in which it can be swept acro the whole eye by means of appropriate muscles and tendons (see cut at eyel ), but in many others it is rudimen tary or wanting. In e ential character it is a fold of the conjunctival mucous membrane which when little developed, or when not in action, lies at the inner canthus of the eye. Obturator membrane. (a) The membrane or ligament nearly closing the obturator foramen. (b) The occlud ing membrane of the fetal brain which closes the upper part of the fourth ventricle. - Pituitary membrane, the mucous membrane of the nose; the membrane lining the nasal pa ages, continuous with that of the pharynx, ear, eye, and various sinuses of the skull. In a part of this membrane ramify the nerves of smell. Also called Schneiderian membrane. Pupilary membrane, a delicate transparent vascular membrane of the fetal eye which closes the pupil for a time, and divides the space in which the iris is suspended into two distinct chambers. It is sometimes persistent, causing blindne . - Schneiderian membrane, the pituitary membrane: so called from the anatomist Schneider, who first showed the nasal mucus to be the product of this membrane, not of the brain, as had before been supposed. Semilunar membrane, in ornith., the membrane of the syrinx or lower larynx. It is a delicate, highly vibratile membrane, with a free concave upper margin ascending in the trachea from the pe ulus or cro -bar of the syrinx, and constitutes a part of the vocal organs, like a vocal cord of the larynx of a mammal. - Serous membrane, a thin membrane of connective ti ue, of mesoblastic origin, lined with a simple layer of flattened epithelial cells. These cells are joined together along lines which are sometimes straight but usually sinuous or jagged. Between them here and there are openings (stomata) of lymphatic ve els. Membranes of this kind line certain cavities of the body, and are reflected over the contained viscera, forming in this way a shut sac, moistened with lymph and communicating with the lymphatic ve els through the stomata. The best examples of serous membranes are the pleuræ, the pericardium, the peritoneum, and the tunicæ vagina les. - Sub radular membrane, a membrane situated under the radula or lingual ribbon of the odontophore of a mollusk. - Synovial membrane, the membrane which lines the joints and secretes synovia or synovial fluid, the glairy substance which lubricates the joint and facilitates its movements. The membrane pa es gradually into the articular cartilage. Such membranes consist chiefly of connective ti ue, with ve els and nerves, covered here and there with patches of epithelial cells. - Tectorial memlear canal of the ear, lying above and allel with the basilar membrane, extending outward from the limbus spiral is part way toward the outer wall of the cochlea, and covering the Cortian organ, upon the rods of which it rests. It is thin at its origin at the limbus spiral is, then thickens, and again tapers toward the free outer extremity. Also called membrane of Corti. - Thyrohyoid mem membrane brane, the fibrous membrane which connects the hyoid bone with the thyroid cartilage. - Tympanic membrane, the membrane which occludes the external meatus of the ear and separates it from the middle ear. - Undulating membranes, simple membranous bands, one margin attached, the other free, exhibiting undulatory motion. Mi crographic Dict. Vibratile membrane. Same as semi lunar membrane.- Vitelline membrane, the proper coat or wall of an ovum, inclosing the vitellus or yolk: it corresponds to the cell-wall of any other cell. Also called zona pellucid a, from its pellucid appearance in some cases, as in the human ovum.