On Dark Carnival's Stadium Entrance, you can also have another way to summon the Horde. Also in Left 4 Dead 2, there is a new mutation mode called Versus Survival which is a mix of both Survival, and Versus mode.
A serous membrane is a thin membrane that helps body parts move more easily and reduces friction between them. Also known as serosa, these membranes are found throughout the body, usually surrounding organs. There are several medical conditions associated with the serous membane, some of which can be life threatening.
The lining on the surface of the heart and the pericardial sac that surrounds the heart. Serous membranes consist of a simple squamous epithelium called mesothelium and a thin underlying layer of areolar connective tissue. The thinness of serous membranes allow fluid to seep through and form a transudate.