What is this symbol ?

[Vitxiem]

Hi, I came across this strange symbol
It's in the Atmega328p datasheet, Ports as General Digital I/O, Figure 14.2
Part of the circuit:

I've been searching for it for an hour. But got no result.

 

[Harald Kapp]

Welcome aboard EP.

The symbol stands for a transmission gate, an analog switch made from an NMOS/PMOS transistor pair.