ANATOMY OF MEGAPTERA LONGIMANA. 



173 



PART lY.— continued. 



Ear Bones, Mandible, and Hyoid. 



Page 



23. Ear Bone, . . . .173 



24. Measurements of Mandible, 176 



25. Characters of Mandible in 



comparison with B. mus- 

 culus, . . . .177 



Page 



26. Relations of Mandible to 



Skull, . . . .184 



27. Hyoid Bone, . . .185 



28. Characters of Hyoid in com- 



parison with B. musculus, 185 



23. Ear Bone— Tympanic. — The following are the dimen- 

 sions of the tympanic bone in Megaptera, and in the 50-feet- 

 long B. musculus, in inches : — 



The tympanic bone of Megaptera may be distinguished from 

 that of B. musculus by the following characters: — 1. It is 

 shorter in proportion to its breadth than in B. musculus. 

 2. As seen from below, in B. musculus the breadth of the bone 

 at the lobe in front of the median constriction on the outer side 

 is nearly as great as at the lobe behind it. In Megaptera the 

 constriction is farther forward, and the breadth is considerably 

 less before than behind the constriction. 3. Viewed from behind, 

 the surfaces in B. musculus are seen to slope from the inferior 

 border like a gable-roof. This flattening is wanting in Megap- 

 tera, the whole of the under surface being convex transversely, 

 except slightly before and behind. 4. Seen on the inner sur- 



