234 PEOFESSOE FLOWEE ON THE EECEXT ZIPHIOID WHALES. 



fragments of bone, apparently dismemberments of the frontal ; SO, supraoccipital ; 

 BO, basioccipital ; BS, basisphenoid ; PS, presphenoid ; Pt, pterygoid. 

 Fig. 8. Inner surface of the right ramus of the lower jaw. 

 Fig. 9. Hyoid bones. BH, basihyoid ; TE, thyro-hyoid. 



Fig. 10. Dorsal surface of the left manus, some of the terminal phalanges missing. 

 R, radius; XI, ulna; s, scaphoid; I, lunar; c, cuneiform; td, trapezoid; 

 m, magnum ; u, unciform ; I to V, the five digits. 

 All one sixth of the natural size. 



PLATE XXIX. 



Fig. 1. United right periotic and tympanic bones of Berardius arnouxi, outer surface. 



Fig. 2. The same bones, under surface. 



Fig. 3. The periotic bone, upper surface. 



Fig. 4. The periotic bone, under surface. 



Fig. 5. The tympanic bone, upper surface. 



Fig. 6. The united periotic and tympanic bones of Hyperoodon rostratus, outer surface. 

 From a specimen in the Museum of the University of Cambridge. 



Letters to all the above figures : — -per, periotic ; ty, tympanic ; a, principal or posterior 

 articular surface between these bones ; a!, broken surface where the two bones had 

 been united ; e.a.m, external auditory meatus, closed in life by the membrana tympani ; 

 ep.l, external posterior lobe of the tympanic; ip.l, internal posterior lobe of the 

 tympanic ; e, groove for the Eustachian tube ; m, posterior bony process corre- 

 sponding in its relations with the mastoid of other mammals, but united with the 

 tympanic; i.a.m, internal auditory meatus; a.f, aqueduct of Fallopius; f.o, fenestra 

 ovalis; f.r, fenestra rotunda; a.l, anterior lobe of the periotic; m.l, its middle 

 lobe ; p. I, its posterior lobe. 



Fig. 7. Median vertical antero-posterior section of the anterior tooth of the right side. 



c, cementum ; d, dentine ; g, globular dentine ; p, remains of pulp-cavity. 



Fig. 8. Corresponding section of the posterior tooth of the same side. 

 All of the natural size. 



