sphenolepIs

[Pref. spheno-, and Gr. lep is Paleont.: A genus of Esocide, with long wedge shaped scales, from the freshwater limestone of Aix and the gypsum of Paris. sphèn-on-chus ( pl. sphēn-on-chi, s. [Prefix sphen-, and Gr. ongkos a hook, a barb.] Palæont.: One of the hooked cephalic dermal spines of Hybodus and Acrodus, specimens of which genera are in the British Museum, South Kensing ton, showing the spines (not more than four in any individual) in situ , but it is not known whether four was the normal number, or if they occurred in all the species. On these spines Aga iz founded a genus Sphenonchus, which he placed with the Hybodontide. This has, of course, lapsed, and the word Sphenonchus has now no generic signification. sphèn-oph-1-lům, s. [Prefix spheno- , and Gr. phyllon a leaf.] Palæobot .: A genus of Equisetaceae(?), allied to (or, according to Mr. Carruthers, identical with) Calamities. They have verticillate leaves, like reversed wedges. Four species from the Carboniferous rocks of Europe; others from North America. sphēn-op-ter-is, subst . [Pref. spheno- , and Gr. pteris a kind of fern.] d2. The the diameter by the circumference of a great circle; or it is equivalent to the area of four great circles. Denoting the radius of the sphere by r, and its diameter by d, we have the following formula for the surface: 8=4pr2= pd2 =3-14159 volume of a sphere is equal to the product of its surface by one-third of its radius. It is also equivalent to two-thirds of the volume of its circumscribing cylinder. The following formula gives the value of the volume of any sphere, whose radius is rand diameter is d : v =pr3. Spheres are to one another as the cubes of their diameters. 3. Logic : The extension of a general conception; the individuals and species comprised in any gen eral conception. (1) Armillary sphere : [ARMILLARY.] (2) Doctrine of the sphere : The application of geometrical principles to geography and astron omy. (3) Harmony (or music) of the spheres : [HARMONY, (4).] (4) Oblique sphere: Spherical projection : The case in which the projection is made upon the plane of the horizon of any place not on the equator, or at the poles. (5) Parallel sphere : (PARALLEL, a .] (6) Projection of the sphere: [PROJECTION.] (7) Right sphere: [RIGHT, а.] (8) Sphere of influence : A phrase used to denote nately from the base. From the Devonian to the Wealden. In the Carboniferous rocks there are thirty-four species, and in the Jura ic seventeen.