The group $Amniota$ includes:

Name the subphyla of the phylum Chordata.

Which of the following cannot be considered a characteristic of non-chordates?

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R)$.
Assertion $(A)$: All vertebrates are chordates but all chordates are not vertebrates.
Reason $(R)$: Notochord is replaced by vertebral column in the adult vertebrates.
In the light of the above statements,choose the most appropriate answer from the options given below:

In chordates,the brain is formed from which of the following structures?

What is the correct classification of Ascidia?