206 NORTH-CAROLINA GEOLOGICAL SURVEY. 



curved, scarcely forming a hook. Behind the convex part it is 

 very regular, but the beginning of the thinner expanded part 

 is formed by a rounded ridge which may be traced from one 

 extremity to the other. It is far less angular, and more regular 

 than the preceding. It is 2f inches long ; greatest width 1 

 inches. 



This ototite is one of the most common in the miocene 

 beds. Unfortunately, in all these specimens, the thin ex 

 panded over-arching part is broken off, but it is evident that 

 in this case this part was very limited. 



The two smallest are perforated by boring moluscks, a fact 

 which shows that instinct is sometimes at fault. 



It is probably impossible in the present state of our knowl 

 edge of the anatomy of those extinct whales, to refer them 

 to the species to which they belonged. That the foregoing 

 ear-bones I have described belonged to different species of 

 the whale, there can be no doubt. 



Few extinct species of balaena are known to belong to the 

 miocene period besides the orycterocetus of Leidy. 



SUMMARY 



Of the characteristics of the three foregoing species, derived 

 from a comparison with each other, and with the three 

 which have been described, l&amp;gt;y PROF. OWEN. 



The B. mysticetoides differs from B. affiuis Owen, in the 

 much greater extent of the overarching wall and the well de- 

 tined limits, and greater prominence of the involuted part; 

 this part also bears a much greater proportion to the whole of 

 the organ than it does in the affinis. 



The B. deiinita Owen is very strikingly truncated at its 

 posterior end, and has also its thick involuted part much less 

 in proportion than in the B. mysticetoides, and its thin over 

 arching border is also much less in extent. 



It differs from the B. gibbosa, Owen, in most of the charac 

 ters just stated ; particularly the extent of the overarching 

 wall, its thick convex part is much less prominent ; but it re- 



