Jointed legs, exoskeleton of chitin, haemocoel.

Explanation

**Step-by-Step Solution:**

1. **Identify the Characteristics**: The question mentions three specific characteristics: jointed legs, an exoskeleton made of chitin, and a hemocoel.

2. **Phylum Identification**: These characteristics are indicative of a specific group of animals. In this case, they are characteristic features of the phylum **Arthropoda**.

3. **Understanding the Terms**:
- **Jointed Legs**: This refers to the segmented limbs that allow for flexible movement, which is a defining feature of arthropods.
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