This escellent site about Cumaceans gives access to a key to Cumacea using the IntKey software that is not useable except by Windoze:
To use these datasets, simply download the zip files and extract them to your hard drive. Open Intkey and point to the initiation file in the directory.
Downloading and using Intkey
To retrieve information, you need the program Intkey and data files. Download the program first. It is recommended that you install the current version of Intkey. You must have Windows 95/98/ME, NT, 2000 or XP. Using these platforms, Intkey can read the data files from the Internet, and afterwards save them on your hard disk.
Please use Internet Explorer only