Separate the crab meat from its shell, and promptly dispose of the shell in the garbage can outdoors. Begin heating water for the fettucine. Melt the butter in a saute pan big enough to accommodate the pasta. Add the cream and bring the mixture to a slow boil. Cook for a minute or two, stirring, and then remove it from the heat. Make the fettucine in the usual way and add it to the boiling water. While the pasta is cooking, return the sauce to the stove at low heat. When the fettucine is nearly done, quickly drain it and incorporate it gently with the sauce. Mix in the crab meat, then the cheese. Sprinkle the pepper and nutmeg over the fettucine and stand clear.