A note with half the value of a quaver. One sixteenth of a semibreve. That is, a semiquaver is a sixteenth note.
___ ___
| /###\ /###\
|\ |#####| |#####|
| \ |\###/ |\###/
|\ ) | |
| \ | |
| ) | |
| | |
| | |
___ | | |
/###\| |___________________|
|#####| | |
\###/ |___________________|
That's
two tails.