Public lstForms As New List(Of String)
    Sub GedForms()
        Dim myAssembly As System.Reflection.Assembly = System.Reflection.Assembly.GetExecutingAssembly()
        Dim types As Type() = myAssembly.GetTypes()
        For Each myType In types
            If myType.BaseType.FullName = "System.Windows.Forms.Form" Then
                Dim s As String = myType.Name
                lstForms.Add(s)
            End If
        Next
    End Sub

Dim frm As Form = Typeof(Form).IsAssignableFrom(myType)

If Typeof(Form).IsAssignableFrom(myType) Then
  lstForms.Add(myType.Name)
End If