Sime~Gen Novels

Written by Jacqueline Lichtenberg and Jean Lorrah
The novels take place in a post apocalypse Earth. Through some cataclysm, mankind had split off into two forms, the simes, and the Gens. The Simes developed tentacles on their forearms which they used to extract selyn, a vital life-giving energy from the Gens each and every month. (Invisible to the naked eye and only detectable through the lateral tentacles of the Sime) A Gen appears to all outward extents, like a normal human. In the early history of the timeline, the selyn is taken from the Gens by force, causing a painful death by nerve burn. Many of the stories involve learning and teaching new ways to approach this process, so that both can survive. In the system, they were looking toward a Malthusian apocalypse, Zelerod's Doom, where due to the increasing sime population and longevity the last Gen would eventually be Killed, leading to the rather painful death by attrition the very next month by the entire sime population.
The major sime characters of the series are the channels, simes who find that they have two reservoirs to hold selyn, allowing them to engage in secondary functions, primary of which is to distribute selyn to other simes.
The published Sime~Gen novels are, in published order:
House of Zeor (#1 1974)
Unto Zeor, Forever (#2 1978)
First Channel  (#3 first pub. 1980)
Mahogany Trinrose (#4 1981)
Channel's Destiny (#5 1982)
RenSime (#6 1984)
ambrov Keon (#7 1986)
Zelerod's Doom (#8 1986)
Personal Recognizance (#9, 2010, publ. with #10 in Wildside Double)
The Story Untold and Other Sime Gen Stories (#10 2010)
To Kiss or to Kill (#11, 2011)
The Farris Channel (#12, 2011)
Fear and Courage: Fourteen Writers Explore Sime~Gen (#13  2015)
A Change of Tactics: (Clear Spring
Chronicles #1) (# 14 2017)