Which of the following statements is incorrect about the circulatory system of earthworm?

Options

A. Pheretima represents a closed type of blood vascular system.
B. Blood glands are present in 4th, 5th, and 6th segments, they produce blood cells and hemoglobin dissolved in plasma.
C. There are four pairs of hearts in earthworm present in 7th, 9th, 12th, and 13th segments.
D. ln the dorsal vessel, blood flows in forward direction and is without valves.

Answer

To determine which statement is incorrect about the circulatory system of the earthworm, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding the Circulatory System of Earthworm**:
- Earthworms have a closed circulatory system, meaning that blood is contained within blood vessels.

2. **Analyzing Option 1**:
- **Statement**: "Ferritima posthuma represents a closed type of blood vascular system."
- **Evaluation**: This statement is true. Earthworms have a closed circulatory system with blood vessels and capillaries.

3. **Analyzing Option 2**:
- **Statement**: "Blood glands are present in the fourth, fifth, and sixth segments; they produce blood cells and hemoglobin dissolved in plasma."
- **Evaluation**: This statement is also true. The blood glands in these segments produce blood cells and hemoglobin, which is dissolved in plasma.

4. **Analyzing Option 3**:
- **Statement**: "There are four pairs of hearts in the earthworm that are present in the 7th, 9th, 12th, and 13th segments."
- **Evaluation**: This statement is true. Earthworms have four pairs of hearts located in these specific segments.

5. **Analyzing Option 4**:
- **Statement**: "In the dorsal vessel, blood flows in a forward direction and without valves."
- **Evaluation**: This statement is incorrect. While blood does flow in the forward direction in the dorsal vessel, it actually contains valves that help regulate blood flow.

### Conclusion:
The incorrect statement about the circulatory system of the earthworm is **Option 4**.

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