Ornithoid lifeforms were an advanced, sentient ornithoid species from outside the Milky Way Galaxy. Without the amplification of their substantial mental abilities via their transmuter technologies, their tiny bodies and fragile physiology left them unable to survive in environments considered suitable for humanoids.
Answering to the Old Ones, two Ornithoid explorers, Korob and Sylvia, set up an observation outpost on Pyris VII during the mid-23rd century. They encountered the USS Enterprise and held members of the crew for study in 2267. Both died after James T. Kirk destroyed their means of support in an effort to escape capture. (TOS: "Catspaw")
The Ornithoids from "Catspaw" were represented by puppets, whose strings were clearly seen on screen.
The image on the PADD was taken from the Star Fleet Medical Reference Manual, written by Geoffrey Mandel and illustrated by Doug Drexler, which also has further notes on the image: the six horizontal circles are labeled A to F, the six vertical circles G to L.
The book identifies the twelve letters as: