Where is there irony in "The Monkey's Paw"?

In the story "The Monkey's Paw" by W.W. Jacobs, the irony, or difference between what the Whites think will happen and what actually happens, is that the monkey's paw, an object of their desires to have wishes fulfilled, becomes a curse rather than a blessing.

This ironic outcome is foreshadowed in the words of Sergeant Major Morris, a guest of the Whites whose demeanor is nervous when he recounts his possession of the monkey's paw which was passed on to him.  For instance, he admits to the paw's giving of three wishes, but his face whitens and his teeth tap against the glass from which he drinks; then, he replies to the query as to what the third wish was, "I don't know what the first two were, but the third was for death.  That's how I got the paw."  Solemnly, he urges the Whites not to keep the paw, but to "let it burn." 

Of course, the greed of the Whites supercedes the fear of the magic of the paw.  They make a wish for a grand sum of money, a wish they receive; however, ironically, Mr. and Mrs. White lose their son Herbert in the fulfillment of the wish.  For, the two hundred pounds is the amount of payment due on the life insurance policy for Herbert, who is killed in an accident at work.  In another dramatic ironic twist, the lonely parents wish for their son back, but he returns a mangled, hideous creature; so, Mr. White must wish him dead to spare Herbert and his wife the agony of his living a tortured life.