Bull. U. S. B. F. 191 2. 



Plate LXI. 



OI'ERCri,VM , . . 



PREOPERCULUM. 



CHEEK MUSCLE IN SECTION-... 



nil.l, FILAMENTS OF 4TH ARCH 



HEAD OF KIDNEY 



ESOPHAOrs 



ORAL :mkmbrane 



ITH rkanchiai. akch 



3KT) BRANCHIAL ARCH 



;nd HRANCHIAL ARCH 



.1ST nRANCHIAL AKCH 



TlVOJn CORN!' 



Fig. 15. — Composite picture of lateral and long-itudinal distribution of normal thyroid in the Salmoniihe. with vessels. 



ORAL MEMBRANE ■ I \ 



TEETH OF TONGUE : ;' I \ 



i BASIHYAL : i ; ! 



TONGUE CARTIL'aGE; 



HYPOHYAL ; 



1ST COPULA (CARTILAGE) 

 1ST BASI BRANCHIAL 

 • 2ND BASIBRAXCHIAL 



; ; 2ND COPULA (CARTILAGE) 



: MUSCLE '; ': 4TH BASIBRAXCHIAL 



: I '"'V:.-;- -i... 3RD BASIBRANCHIAL 



.i 3RD COPULA (CARTILAGE) 



-:._ '; " -i .... VENOUS sinus 



i T'-i, ]" -. ESOPHAGEAL MUCtlSA 



■ ; : ^t'fSCI.E" AND' ARKOLAR TISSUE 



SYMPHYSIS OF DENTARY 



ISTHMUS ; ; : 

 .MUSCLE : : ; • : 



i : JIGULAK PIT 



BRANCHIAL SEPTUM 

 HYPOHVAI, SYMPHYSIS 



MUSCLE -: ; 



■ UROHYAL 



BRANCHIAL SPACE 



^EPITHELIUM 

 SUBMUCOSA 

 SYMPHYSIS OF CLAVICLE— CORACOIH PAIRS 

 VENTRAL AORTA 



Fig. 16. — Longitudinal and dorso-ventrnl distribution of thyroid in the Sahuonidx-. 



