Summary of Findings So Far With Respect to Clement of Alexandria's Authorship of an Account of the Death of the Apostles and Its Relationship to the So-Called "List of the Apostles" (Tony Burke)

1. The name "Clement" appears at the beginning of some version of the list i.e. it is attributed to "Clement." 

2. The name "Clement" appears at the end of some versions of the list i.e. it is attributed to "Clement." 

3. "Clement of Alexandria" and "the Fifth Book of the Hypotyposeis" is attributed to some of the List of the Apostles specifically the list of the Seventy. 

4. The Fifth Book of the Hypotyposeis contained both information on the Twelve and the Seventy. 

5. Codex Marcianus attributed the entirety of the information of the Twelve and the Seventy to the Fifth Book of the Hypotyposeis.

6. Codex Marcianus and many other versions of the information identify Mark as an apostle, specifically the ninth, in a consistent pattern.

7. No tradition associated with the Fifth Book of the Hypotyposeis identifies Mark as one of the Seventy.

8. At least one other tradition associated with the List of the Apostles (outside of those traditions that physically list Mark as an apostle or the ninth in a list of twelve apostles) makes reference to Mark as an apostle (specifically in a list of companions of Paul where Mark is referenced as "the apostle Mark"). 

My conclusion, is that it is likely that Clement made reference to Mark being an apostle in the Fifth Book of the Hypotyposeis.