Perseus Books announced last week that Thomas Allen will join the company December 6 as chief financial officer. Formerly a senior finance v-p at Random House Inc., Allen will replace Thomas Kilkenny, who is leaving the company. Perseus CEO David Steinberger hinted strongly at acquisitions in his explanation of the change, citing Allen's experience with the merger between Random House and the former Bantam Doubleday Dell in 1998. "As Perseus grows, organically and through acquisition," he said, "only a handful of people in this industry" can manage the complicated effects of a merger or other growth.