linq - How to filter a collection of delegates based on their parameter's generic type in C#? -

i have collection of delegates:

ilist<action<isomeinterface>> _delegates = new list<action<isomeinterface>>(); 

and method* add delegates it**:

public void adddelegate<t>(action<t> del) t : isomeinterface {     _delegates.add(si => del((t)si));    } 

now want filter delegates collection based on concrete type delegate constructed with:

var adelegates = _delegates.where(d => d action<someinterfaceimpla>); foreach(var del in adelegates) {    .... } 

which return delegates, not action<someinterfaceimpla> delegates. question is, predicate should used in where clause correct subset filtering? full code example available here.
_{* fluent api (generic) method using hence use of generic type here
** based on answer here}

this not prettiest thing ever, works

    var adelegates = someclass.delegates.where(d =>          d.method.declaringtype.generictypearguments.firstordefault().isassignablefrom(typeof(someinterfaceimpla)));