Elasmobranchii vs Selachii

Elasmobranchii and Selachii both are nouns.

Word	Noun	Adjective	Verb	Adverb
Elasmobranchii	Yes	No	No	No
Selachii	Yes	No	No	No

As nouns, Elasmobranchii and Selachii are synonyms defined as:

Other synonyms of Elasmobranchii include subclass Elasmobranchii, subclass Selachii.

Elasmobranchii (noun)	Selachii (noun)
sharks, rays, dogfishes, skates	sharks, rays, dogfishes, skates