ART. 19 



A MIOCENE PORPOISE FEOM MARYLAND— KELLOGG 



29 



combined facets articulate with corresponding facets on the incus. 

 A deep groove crosses the head of the malleus (fig. 13) in an oblique 

 direction from the outer to the inner margin, and divides the head 



XS>(4 



15 15 



^r 20 



19 



Figs. 8-20. — Left Malleus, Incus, and Stapes of Kentkiodon Pbbnix. X 5. Cat. 

 No. 8060. The Same Abbreviations Are Used on Numbers 8 to 20 foe the Fol- 

 LOWiNG Structures : c. b., Crus Breve ; c. I., Crus Longum ; f., Articular Facet ; 

 /. p., Foot Plate of Stapes ; h., Head ; /. a., Intercrukal Aperture ; 1, lamina ; 

 viti.. Manubrium ; p. a., Processus Anterior ; P. m.. Processus Muscularis ; ec. 

 Scab for Insertion of Stapedius Muscle; t., Tubercle; u.. Umbo. Fig. 8, Extebnal 

 View of Malleus ; 9, Ventral View of Malleus ; 10, Dorsoexternal View of Mal- 

 leus AND Incus in Position ; 11, Ventrointernal View of Malleus and Incds in 

 Position ; 12, Internal View of Malleus ; 13, Dorsal View of Malleus ; 14, Ven- 

 tral View of Incus ; 15, External View or Base of Incus ; 16, Internal View or 

 HEAD of Incus ; 17, Posterior View of Incus ; 18, Posterior View of Stapes ; 19, 

 Vestibular View or Footplate of Stapes ; 20, Head of Stapms 



into two surfaces — the tubercle and the combined facets for the 

 incus. The process or tubercle at the anterior end of the head is 

 short and stout, and from it on the internal side arises the manu- 



