Dusky smooth-hound Dusky smooth-hound The dusky smooth-hound ("Mustelus canis"), also called the smooth dogfish or the dog shark, is a species of houndshark in the family Triakidae. This shark is an olive grey or brown in color, and may have shades of yellow or grayish white. Females live to 16 years and males have a lifespan of 10 years. "M. canis" was the first shark recognised to have viral infections. "M. canis" can be known as smooth dogfish, Atlantic smooth dogfish, dusky smooth-hound, grayish, nurse shark, smooth dog, or smooth-hound. It was originally named "Squalls canis". In Latin, "mustelus" translates to weasel
Smooth scheme only if the morphism "X" → Spec "k" is smooth. A smooth scheme over a field is regular and hence normal. In particular, a smooth scheme over a field is reduced. Define a variety over a field "k" to be an integral separated scheme of finite type over "k". Then any smooth separated scheme of finite type over "k" is a finite disjoint union of smooth varieties over "k". For a smooth variety "X" over the complex numbers, the space "X"(C) of complex points of "X" is a complex manifold, using the classical (Euclidean) topology. Likewise, for a smooth variety