Plegadis is a bird genus in the family Threskiornithidae. 

Pelecanus: Greek pelekan, pelekanos pelican.

Threskiornis Greek threskeia religious worship (threskeuo to worship); ornis bird. 
The Sacred Ibis Threskiornis aethiopicus was venerated by the ancient Egyptians for its crescent-shaped bill and bright white plumage. They considered it to represent Thoth the moon god.

The genus name derives from Ancient Greek plegados meaning "sickle", referring to the distinctive shape of the bill.

1/ Glossy ibis (Quắm đen, Plegadis falcinellus)
The scientific name derives from Ancient Greek plegados and Latin, falcis, both meaning "sickle", referring to the distinctive shape of the bill.