At the end of later editions of William C. Fowler's Common School Grammar (rev. ed., 1867) is a work by Francis A. March, A Parser and Analyzer for Beginners, with Diagrams and Suggestive Pictures (1869). These diagrams are similar to Clark's, but have square boxes where Clark has ovals. March acknowledges in the preface that the diagrams are adapted from Clark's system and says they are used with permission. The scan here comes from an 1884 stereotype edition.
Sample diagrams of coordinate conjunctions (pp. 60-61)