gnome-themes-extras software package provides extra themes for the GNOME desktop, you can install in your Ubuntu 14.04 LTS (Trusty Tahr) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gnome-themes-extras
gnome-themes-extras is installed in your system.
Make ensure the gnome-themes-extras package were installed using the commands given below,
$ sudo dpkg-query -l | grep gnome-themes-extras *
You will get with gnome-themes-extras package name, version, architecture and description in a table
| Distro | Ubuntu 14 04 lts trusty tahr |
| Section | GNOME |
| Package | gnome-themes-extras |
| Version | 2.22.0-3 |
| Description | extra themes for the GNOME desktop |
| Sub Section | GNOME |