"I quite agree with you," said Olive; "I know from having had the same feeling before, that unless we eat some of these little salt biscuits, and talk about something interesting, in a very few minutes you and I will be sea-sick--which is the hungriest, emptiest sickness possible." "I thought the feeling was a little more puffy than real hungriness," said Dodo, chewing her biscuit in great haste and having some trouble in swallowing it. "May not we men have some too?" asked the Doctor, looking drolly at the boys, who were glancing longingly at the biscuits, but were too proud to confess their feelings. "Not that we feel ill--oh, no! Merely for company, you know. "Now while you munch away, I will talk Duck to amuse you; eating and Duck talk go very well together, for the Duck is chiefly to be considered as food. You all know what a well-rounded, compact body a Duck has; do you remember having seen one carved, and how very hard it was to cut off its legs?" "Yes, I do," said Nat. "Sometimes the Duck almost bounces off the dish, and then, father says things--at least, I mean, he says he wishes that people who go shooting and send him presents of Wild Ducks would send a carving map and a good sharp knife with them; but I never understood what he wanted the map for." "To find the joints, my boy," laughed the Doctor, as if he had a sympathetic feeling for carvers who find themselves in front of a tough Duck or Goose, no matter how well they know where the joints ought to be found. "A Duck's legs are very short, and not only set far back on the body, but sunk into the skin quite up to the knees; so that the joints are very hard to find. This is planned to give the Duck more strength and ease in swimming, when the legs act like paddles. All Ducks' feet have three long toes in front and a short one behind, the front toes being loosely joined by two skin flaps which stretch between them when spread apart, making what we call web-feet." "Something the way frogs' feet are?" asked Nat. "Very much upon the same plan. Then Ducks have wide flat beaks of various shapes, with a sort of nail bent over like a hook at the end, and all along each side is a double row of little teeth, to help them take their food. Their stiff, pointed wings are quite strong enough to lift their heavy bodies off the ground or water into the air, and keep up an even flight, often more rapid than the swiftest express train." "What do Wild Ducks eat?" asked Dodo, "seeds or bugs or fish?" "They eat all those things and many others too, according to their various habits, which are as different as the expression of their faces or the color of their features. If you look at a case full of Wild Ducks in a museum, you will find that no two have the same-shaped head, or expression. Some look silly, some sly, while others seem either proud or inquisitive."