Srimad Bhagavatam Canto 11, Chapter 21, Text 41

SB 11.21.41

gayatry usnig anustup ca
 brhati panktir eva ca
tristub jagaty aticchando
 hy atyasty-atijagad-virat
 
Translation: 
 
The Vedic meters are Gayatri, Usnik, Anustup, Brhati, Pankti, Tristup, Jagati, Aticchanda, Atyasti, Atijagati and Ativirat.
 
Purport: 
 
The Gayatri meter has twenty-four syllables, the Usnik twenty-eight, the Anustup thirty-two, and so on, each meter having four more syllables than the previous one. Vedic sound is called brhati, or most expansive, and thus it is not possible for ordinary living entities to understand all the technical details in this matter.
Srimad Bhagavatam Canto 11, Chapter 21, Text 38-40
Srimad Bhagavatam Canto 11, Chapter 21, Text 42