Elliptical Galaxies (EG's) are as the name suggests, elliptical.
The level of ellipticity varies from EG's that are completly
spherical to
cigar shaped EG's. A spherical EG
is called an E0, the more non-spherical the higher
the number it gets. E7 is about as non spherical as you are likley to get.
Due to the fact that our view of elliptical galaxies
is two dimensional as we are looking at the plane of the sky
for a while it was quite hard to determine whether E0's
were actually round or rather E7's viewd along the axis.
This problem was solved with the advent of CCD cameras.
Using these devices the isophotes of the galaxy could be
mapped. The isophotal map gives unambigious information
about the shape of the galaxy when you connect it to a dynamical model.
It was first thought that EG's had no gas or dust
and were compsed of only dark matter and stars.
This is no longer considered to be true as we can clearly see a lot of dust in galaxys such as the sombrero galaxy.
EG's are both the most massive galaxies we know of and the least massive. The central galaxy in the Abell cluster may have as much as
10^13 solar masses. Such a centrally dense region
is called a CD galaxy.
There are also Dwarf Ellipticals whoose mass can be as small as 10^6 solar masses.
The most interesting thing about EG's is that there is a three family parameter space in which all EG's lie in a plane. This is called the fundamental plane. The parameter space is luminosity, density and average central velocity