Seneca Cameras, Seneca Camera Mfg. Co., (Rochester, NY), Catalog P, undated c. 1916, ~5"x8", 72pp

From 1906 through 1913, Seneca established a routine of publishing one catalog per, usually "numbered" using a sequential letter of the alphabet, and often also bearing a copyright date. For instance, Catalog L had a copyright of 1912, and Catalog M had a copyright of 1913.  It is a fair inference that Catalog N is for 1914, O is for 1915, and P is for 1916.