The Continental Op (1974) was an important book in the field of Hammettology. It was, I believe, the first hardcover publication of the seven Op stories contained herein, and, at the time of its publication, most had been out of print for more than twenty-five years.
UPDATE! Don Herron wrote to say these are indeed the Dannay versions of the stories. See his blog post HERE.
Not counting the two serialized novels (each comprised of four connected novelettes), there were 28 adventures of the Continental Op. The nine best, as selected by Lillian Hellman, had already been reprinted in The Big Knockover (1966), and the seven collected here could fairly be called the best of the rest.
So what's the difference? The earliest tales, mostly from 1923, are competent, straight-forward and well-written mysteries, but the Op displays very little personality. In fact, he's nearly invisible.The stories in this book, most from 1924, show the Op in transition. Hammett's style is growing more distinct, and the Op's character is beginning to emerge. In the later stories, and particularly in the related novelettes "The Big Knockover" and "$106,000 Blood Money," and the novel Red Harvest, the Op emerges in all his hardboiled glory. Based on style, I believe that the two last stories in this volume, appearing in Black Mask in 1927 and 1930, were written much earlier.
Still, second-rate Hammett stories are better than many writers' best, and these are well worth reading. Here's a list of the contents with original publication dates. All now appear in the Library of America volume Dashiell Hammett: Crime Stories and Other Writings.
The Tenth Clew (from Black Mask Jan. 1, 1924)
The Golden Horseshoe (from Black Mask Nov. 1924)
The House in Turk Street (from Black Mask Apr. 1924)
The Girl with the Silver Eyes (from Black Mask June 1924)
The Whosis Kid (from Black Mask Mar. 1925)
The Main Death (from Black Mask June 1927)
The Farewell Murder (from Black Mask Feb. 1930)
Links to this week's Forgotten Books appear (I think) on pattinase.