4 PF.OCEEDIXGS OF THE NATIONAL MUSEUM vol.74 



These resemblances are so important that we are probably justified 

 in regarding the gingival and dental structm'es of Phoconio'ides as 

 representing anatomical stages closely parallel to those through which 

 the corresponding parts in the toothed ancestors of the Mysticeti must 

 have passed. 



EXPLANATION OF PLATES 



Plate 1 



(Buili figures about V-: natural size) 



0. Teelli of Phociciia phocccna from St. George Island, Bearing Sea. No. 



218737, U.S.N.M. 

 &. Teeth of Pliocrenoldcs dalU from Sullivan Island, Lynn Canal, Alaska. No. 



251757, U.S.N.M. Gums partly removed. 



Plate 2 



(Natural size) 



Lateral view of rostrum and mandible of Phocanoides dalli showing gum 

 teeth. (No. 251758, U.S.N.M., Sullivan Island, Lynn Canal, Alaska) 



Plate 3 



(All figures X 5) 



Part of mandibular toothrow of Phoccenoides dalli with gums in place. 

 (No. 243599, U.S.N.M., Wrangell, Alaska) 



a. Outer aspect. 



b. Inner aspect. 



c. Coronal aspect. 



Plate 4 



(Both figures X 5) 



Part of rostrum of PJiococnoides dalli v.-ith gums in place. (No. 243599, 

 U.S.N.M., Wrangell, Alaska) 

 a. Palatal aspect. 

 h. Vertical aspect. 



o 



