Group of animals with a three chambered heart with a partial septum in the ventricle.

Explanation

To answer the question regarding the group of animals with a three-chambered heart with a partial septum in the ventricle, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Heart Structure**: The question specifies animals with a three-chambered heart. This structure typically consists of two atria and one ventricle.

2. **Recognize the Groups**: The main groups of animals that possess a three-chambered heart are amphibians and reptiles.

...