The Morgan classification aka Yerkes classification (a galaxy classification scheme) classifies galaxies by their prominent stellar spectral class(s), then according to morphology, and then according to the angle of view.
|af||a to f class|
|fg||f to g class|
|gk||g to k class|
|D||other rotational symmetry (e.g., lenticular galaxy)|
|cD||extremely large D galaxy|
|L||low surface brightness|
|N||small bright nucleus (N galaxy)|
|Ep||elliptical with dust absorption|
Inclination (as seen from Earth) is indicated by a number 1-7, 1 for face-on to 7 for edge-on.
Note that variants on the terms Morgan classification and Yerkes classification are used for other classifications, such as of stars and galaxy clusters.