hemiprocnidae: tree swifts
group: any number of entities (members) considered as a unit
erythromycin: an antibiotic (trade name Erythrocin or E-Mycin or Ethril or Ilosone or Pediamycin) obtained from the actinomycete Streptomyces erythreus; effective against many Gram-positive bacteria and some Gram-negative