BAL^NOPTERA. 37 



24. Muscle. Section througli the dorsal muscle of the tail of 



a Rorqual, B. musculus, showing the intermingling 

 of muscular and tendinous bundles. 



25. Tendon. A transverse section through another specimen 



from the same animal. The sheath, remarkable for its 

 thickness, has been dissected from the tendon. 



26. Tendon. A larger example from the tail of the same 



animal. The sheath can be seen on a part of the 

 surface, but on another part it has been removed, and 

 the subdivision of the tendon into its constituent 

 parallel bundles is displayed. 



27. Tendon. One of the great tendons from near the end of 



the tail of a Rorqual, B. musculus. 



28. Lip. Transverse section through the lip of a Rorqual, 



probably B. musculus, showing the folds of mucous 

 membrane adjoining the free edge. 



29. Hair. Section through skin of the lower lip of a Rorqual, 



probably B. musculus, showing a number of short, 

 coarse hairs projecting from the surface and forming 

 a beard 



30. (Esophagus, transverse section from a Rorqual 35 feet 



lonof, B. musculus, showino; lono-itudinal folding of 

 the mucous lining. 



31. Heart. Section of auricle of same Rorqual, exhibiting 



the powerful muscular trabecular which project into 

 the cavit}^ which in places form a reticulated 

 arrangement. 



32. Heart. Another section through wall of auricle of the 



same Rorqual. 



33. Heart. Transverse section of a ventricle of the same 



Ror(|ual, showing the reticulated arrangement of the 

 muscular bands. 



3-t. Heart. The long fibrous moderator band, connected at 

 its ends with opposite walls of the left ventricle, of a 

 large Rorqual. 



35. Heart. One half of a semilunar valve of Rorqual, show- 

 ing the arrangement of the strong fibrous bundles 

 which, springing from its attachment, radiate into 

 the substance of the valve. 



30. Heart. Cusp of right auriculo-ventricular valve of 

 Rorqual, B. musculus, showing two columnar carneae 

 and the attachment of the chordtie tendinear. 



