Mitral valve, tricuspid valve, semilunar valve, venous valve.

Explanation

To determine the odd one out from the series of valves: mitral valve, tricuspid valve, semilunar valve, and venous valve, we can analyze each valve's location and function.

### Step-by-Step Solution:

1. **Identify the Mitral Valve**:
- The mitral valve, also known as the bicuspid valve, is located between the left atrium and the left ventricle of the heart. It allows blood to flow from the atrium to the ventricle and prevents backflow.

2. **Identify the Tricuspid Valve**:
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