Cement glands of Lepas and Balanus open over

Options

A. Antennules
B. Antennae
C. Maxillae
D. Maxillules.

Answer

To solve the question regarding where the cement glands of Lepas and Balanus open, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Organisms**: Recognize that Lepas and Balanus are barnacles, which belong to the class Crustacea within the phylum Arthropoda.

2. **Understand Cement Glands**: Cement glands are specialized secretory glands that produce a substance used for adhesion. In barnacles, these glands are crucial for their attachment to surfaces.

3. **Locate the Opening of Cement Glands**: The question specifically asks where these cement glands open.

4. **Evaluate the Options**:
- **Antenules**: These are small, sensory appendages found on crustaceans.
- **Antennae**: These are larger sensory organs, but not where cement glands are located.
- **Maxillae**: These are mouthparts used for feeding, not related to cement glands.
- **Maxillules**: These are also mouthparts, similar to maxillae, and do not relate to cement glands.

5. **Conclusion**: Based on the information, the cement glands of Lepas and Balanus open over the **antennules**.

### Final Answer:
The cement glands of Lepas and Balanus open over **antennules**.

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