Examples
“She not only has no penis, she has no penes, because most male lizards have two penes which make them hemipenes.”
“I'd also imagine that some apes having sex in the past sit on the causal chain which causes Richard Dawkins to imagine things, therefore ape penes are responsible for the illusion of intelligent agency or information in his books.”
“Anostracans are sexually dimorphic; the males have a pair of ventral penes on their genital segments, while the females have a ventral, medial brood pouch to hold their eggs.”
“There are creatures, as it is said, (sit fides penes authorem, but there appears no contradiction that there should be such), that, with language and reason and a shape in other things agreeing with ours, have hairy tails; others where the males have no beards, and others where the females have.”
“Scio quam vana sit et inefficax humanorum verborum penes afflictos consolatio, nisi verbum Dei audiatur, a quo vita, refrigeratio, solatium, poenitentia.”
“Ecclesiastical discipline, penes Episcopos, subordinate as the other.”
“Note 118: VW 3.6, pp. 129 — 32, at 130: "amicum suum qui penes uos est uisitare dilectissimum"; and p. 131: "Ecce regina celi et domini mater patronum huic ecclesie adeo assignatum martirem Willelmum amicum equidem suum uisitare dilectum uenit, coronauit, eique pro libito curandi potestatem contulit." back”
A Tender Age: Cultural Anxieties over the Child in the Twelfth and Thirteenth Centuries
“The words are, penes ittum gloria, penes hunc palma.”
“They want us to believe that all men pull their penes out in public, and not only do we pull them out to take a leak, we also masturbate in front of other people.”
“Vnde principes dicuntur Can, quia penes eos spectat regimen populi per diuinationem.”
Tweets
Looking for tweets for penes.

rolig I think you might have read that wrong, HH. What I saw a moment ago on Wiktionary was this: "(chiefly sciences) Plural form of penis" May 27, 2011
hernesheir "Plural form of science" --Wiktionary May 27, 2011