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.
\n.   The function of the serous membrane is line the body cavities that do not open directly to the outside lubrication.   They allow the organs to slide without friction across the cavity walls and one another as they carry out their routine functions.