Read the following matches about chordates and it's characteristics.
I. Petromyzon - belongs to cyclostomata and are endoparasites on some fishes.
II. Scoliodon - a Chondrichthyes in which teeth are modified placoid scales.
III. Hippocampus - a cartilaginous aquarium fish known as a sea horse.
IV. lchthyophis is a limbless viviparous amphibian with direct development.
Select the incorrect statements ?

Options

A. II and III only
B. III and IV only
C. I and IV only
D. I,III and IV only

Answer

To solve the question, we need to evaluate each statement about the chordates and identify which ones are incorrect.

### Step-by-Step Solution:

1. **Evaluate Statement I: Petromyzon - belongs to cyclostomata and are endoparasites on some fishes.**
- Petromyzon, commonly known as lampreys, are indeed part of the class Cyclostomata. They are jawless fish and are known to be endoparasites on some fish species.
- **Conclusion:** This statement is **true**.

2. **Evaluate Statement II: Scoliodon - a Chondrichthyes in which teeth are modified placoid scales.**
- Scoliodon, also known as the Indian shark, is classified under Chondrichthyes (cartilaginous fish). In these fish, the teeth are indeed modified placoid scales.
- **Conclusion:** This statement is **true**.

3. **Evaluate Statement III: Hippocampus - a cartilaginous aquarium fish known as a sea horse.**
- Hippocampus, commonly known as seahorses, are actually classified as bony fish (Osteichthyes), not cartilaginous fish. Therefore, this statement is incorrect.
- **Conclusion:** This statement is **false**.

4. **Evaluate Statement IV: Ichthyophis is a limbless viviparous amphibian with direct development.**
- Ichthyophis is a genus of caecilians, which are limbless amphibians. However, they are primarily oviparous (egg-laying) rather than viviparous (live-bearing). Thus, this statement is also incorrect.
- **Conclusion:** This statement is **false**.

### Summary of Findings:
- Statement I: True
- Statement II: True
- Statement III: False (incorrect)
- Statement IV: False (incorrect)

### Final Answer:
The incorrect statements are **III and IV**.

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