Long Island Sound snail, the channeled and knobbed whelks. Crustaceans include crabs, shrimp and lobsters. In the Sound there are the green crab (a non-native species first reported in Boston around 1900, but a common crab found on the shore, where it feeds on eastern oysters and soft-shell clams), blue crab, red crab, Jonah crab in deepwater areas, and the Atlantic rock crab, which settles in large numbers along rocky shores, especially around Millstone Point, Niantic Bay and Fishers Island Sound. Other crabs found include the lady crab, spider crabs, and fiddler crabs; hermit crabs and mole crabs are also found. By the
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