This is the Modern Library Paperback series P1 (Crime and Punishment, translated by Constance Garnett with introduction by Ernest J. Simmons). It was the first title in that short-lived numbered paperback line (P1–P67 or so), issued in Spring 1955 at 95¢ with a sewn binding. The series ran only until about 1960 before being phased out in favor of Vintage Books.
The copyright is 1950 (for the text/introduction). That date stayed on the book for years and does not indicate the actual printing year.
The first Modern Library Paperbacks (the numbered P-series, starting with P1 Crime and Punishment) came out in Spring 1955 and were priced at 95¢.
By the Spring 1959 catalog, several of the early titles (including P1) had risen to $1.25. Some listings continued showing $1.25 into 1960 before the series wound down.