Members of phylum Arthropoda lack one of the following features :-

Options

A. External skeleton made of chitin
B. Compound eyes
C. Excretion by malphigian tubules
D. Usually a close type of blood vascular system

Answer

To solve the question regarding the features that members of the phylum Arthropoda lack, we will analyze each option provided.

### Step-by-Step Solution:

1. **Identify the Features of Arthropoda**:
- Members of the phylum Arthropoda are characterized by certain features such as an external skeleton made of chitin, compound eyes, and specific excretory structures.

2. **Evaluate Each Option**:
- **Option 1: External skeleton made up of chitin**:
- This is a true statement. Arthropods possess an exoskeleton made of chitin, which provides support and protection.

- **Option 2: Compound Eyes**:
- This is also a true statement. Many arthropods, including insects and crustaceans, have compound eyes that consist of multiple small visual units.

- **Option 3: Excretion by Malpighian tubules**:
- This statement is correct as well. Arthropods use Malpighian tubules for excretion, which helps in the removal of waste materials.

- **Option 4: Usually a closed type of blood circulatory system**:
- This statement is false. Arthropods generally have an open circulatory system, not a closed one. In an open circulatory system, the blood is not confined to vessels and bathes the organs directly.

3. **Conclusion**:
- Based on the evaluation, the feature that members of the phylum Arthropoda lack is the "usually a closed type of blood circulatory system." Therefore, the correct answer is **Option 4**.