Canary Islands a total of five different species of marine turtle that are sighted periodically in the islands, the most common of these being the endangered loggerhead sea turtle. The other four are the green sea turtle, hawksbill sea turtle, leatherback sea turtle and Kemp's ridley sea turtle. Currently, there are no signs that any of these species breed in the islands, and so those seen in the water are usually migrating. However, it is believed that some of these species may have bred in the islands in the past, and there are records of several sightings of leatherback sea turtle on
History of manifolds and varieties History of manifolds and varieties The study of manifolds combines many important areas of mathematics: it generalizes concepts such as curves and surfaces as well as ideas from linear algebra and topology. Certain special classes of manifolds also have additional algebraic structure; they may behave like groups, for instance. In that case, they are called Lie Groups. Alternatively, they may be described by polynomial equations, in which case they are called algebraic varieties, and if they additionally carry a group structure, they are called algebraic groups. The term "manifold" comes from German "Mannigfaltigkeit," by Riemann. In English, "manifold" refers to