On his own admission Peirce’s priority in his work in semiotics concerned the identification of all possible signs, and it is clearly for this reason that of the two typologies announced in the letter to Lady Welby of 23 December 1908—one yielding twenty-eight classes and the other sixty-six—it was the latter that he found the more interesting, to the complete neglect of the former. And yet contributing to the originality of this particular typology is the fact that after 1906 Peirce appears no longer to employ his phaneroscopic categories as the criteria for establishing the various subdivisions in his classifications, preferring instead three modally organized universes, and, in the period from 1907 on, a growing appeal to the requirement of collateral observation of the object in definitions of the sign—both these factors being associated with a greater understanding of the nature of the dynamic object, particularly in the period 1908-1909. The paper thus seeks to demonstrate the potential for semiotic analysis of Peirce’s neglected 28-class classification system by showing its originality within the fifteen or more typologies he developed between 1866 and 1908. This, it is to be hoped, will compensate for Peirce’s neglect by showing how an examination of the evolving typologies sheds light on the development of his conception of signs and on the shift in the theoretical framework which underwrote it. On his own admission Peirce’s priority in his work in semiotics concerned the identification of all possible signs, and and it is clearly for this reason that of the two typologies announced in the letter to Lady Welby of 23 December 1908-one yielding twenty-eight classes and the other sixty-six-it was the latter that he found the more interesting, to the complete neglect of the former. And yet contributing to the originality of this particular typology is the fact that after 1906 Peirce appears no longer to employ his phaneroscopic categories as the criteria for establishing the various subdivisions in his classifications, preferring instead of three modally organized universes, and, in the period from 1907 on, a growing appeal to the requirement of collateral observation of the object in definitions of the sign-both these factors being associated with a greater understanding of the nature of the dynamic object, particularly in the period 1908-1909. The paper thus seeks to demonstrate the potential for semiotic analysis of Peirce’s neglected 28-class classification system by showing its originality within the fifteen or more typologies he developed between 1866 and 1908. This, it is to be hoped, will compensate for Peirce’s neglect by showing how an an examination of the evolving typologies sheds light on the development of his conception of signs and on the shift in the theoretical framework which underwrote it.