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 determine the incorrect statements about chordates and their characteristics, let's analyze each statement one by one.

### Step-by-Step Solution:

1. **Statement I: Petromyzon - belongs to cyclostomata and are endoparasites on some fishes.**
- **Analysis:** Petromyzon, commonly known as lampreys, indeed belong to the class Cyclostomata. However, they are ectoparasites, not endoparasites. They attach to the outside of fish and feed on their blood.
- **Conclusion:** This statement is **incorrect**.

2. **Statement II: Scoliodon - a Chondrichthyes in which teeth are modified placoid scales.**
- **Analysis:** Scoliodon, commonly known as the dogfish shark, is indeed a member of Chondrichthyes (cartilaginous fishes). Its teeth are indeed modified placoid scales.
- **Conclusion:** This statement is **correct**.

3. **Statement III: Hippocampus - a cartilaginous aquarium fish known as a sea horse.**
- **Analysis:** Hippocampus, commonly known as seahorses, belong to the class Osteichthyes (bony fishes), not Chondrichthyes (cartilaginous fishes). Therefore, describing them as cartilaginous is incorrect.
- **Conclusion:** This statement is **incorrect**.

4. **Statement IV: Ichthyophis is a limbless viviparous amphibian with direct development.**
- **Analysis:** Ichthyophis, commonly known as the caecilian, is indeed a limbless amphibian. However, they are primarily oviparous (lay eggs) and not viviparous (giving live birth). They do exhibit direct development in some species, but the viviparous claim is incorrect.
- **Conclusion:** This statement is **incorrect**.

### Summary of Incorrect Statements:
- Statement I: Incorrect
- Statement II: Correct
- Statement III: Incorrect
- Statement IV: Incorrect

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