I came across this element family recently:
FiniteElement('P', 'triangle', 1) W = VectorFunctionSpace(mesh, 'P', 2)
in this code created by Dr. Logg.
http://www.logg.org/anders/2016/05/11/systems-of-chemical-reactions-in-fenics/
I could not find it in Fenics Manual either:
http://fenicsproject.org/documentation/dolfin/dev/python/programmers-reference/functions/functionspace/FunctionSpace.html
Have a look here: http://femtable.org
Thank you Dr. Mardal!