206 GENERAL ORNITHOLOGY. 
Fig lft 
Fic. 101.— Respiratory and vocal organs of the Rook, Corvus frugilegus, an Oscine Passerine bird; nat. size, 
after Macgillivray. 1. a, tongue; b, basi-branchial, commonly called uro-hyal; c, c, horns of hyoid bone; d, d, 
genio-hyoid muscles; e, e, stylo-hyoid muscles; 7, f, cleido-hyoid muscles; g, h, i, esophagus; j, proventriculus; 
or secretory stomach; hk, gizzard, or gigerium, the muscular stomach; /, m, n,n, intestine, duodenum to rectum ; 
