— no — 



tympanicum is attached to the rest of the skull. Owing to his very slender 

 attachment the bullate tympanic bones easily break off, which explains why 

 they are often missing from skeletons. (In the figure the surface of the 

 fissur is clearly discernible). 



The lower jaw (fig. 6, 7 & 8). 



The mandibula is an elongated piece of bone with an outward arching, 

 measuring a length of 6.20 M. The two mandibles approach each other in 

 front and are there connected by a firm ligamentous tissue. 



On the hindmost quarter of the mandibular bone we perceive the big 

 crown-shaped process (processus coronoideus) whose apex is 83 c.M. distant 

 from the lower margin of the jaw-bone. Quite at the rear-end here is the 

 articulation-process of the mandibula. 



The part of the jaw-bone corresponding with the rising ramus in other 

 mammals, hardly deserves this name here, because this branch is here mainly 

 directed backwards so as to prolong the anterior half of the jaw-bone in 

 the same line, and is even directed a little downwards. 



In connection with this circumstance the articulating condyle of the jaw- 

 bone does not rest in an articular-socket of the squamosum, but remains 

 quite a long distance away from it, separated from it by a thick layer of 

 a partly filamentous partly cartilaginous tissue. This articulation process is 

 divided by a horizontal groove into a bigger upper-part and a smaller lower- 

 part, Midway between the articulation condyle and the coronoid process, at 

 the upper interior surface of the bone, there is a pointed prominence of slight 

 elevation and directed backwards, which conceals an orifice giving access 

 to an interior channel running the whole lenght of the jaw- bone (fig. 7). 

 This canal in its turn communicates with a series of 6 openings elongated 

 in the longitudinal direction of the jaw and situated on the outer and upper 

 edge of this bone. Moreover the interior upper edge of the mandibular bone 

 displays a large number of shallow furrows. 



The lower jaw protrudes quite a long way in front of the intermaxillaria, 

 how far exactly it was not possible to determine by the dead animal, since 

 when found the two halves of the mandibles were no longer in their normal 

 situation. 



I beg leave to insert here a brief discussion relative to the correct position 

 of the mandibles. After the setting up of the Buitenzorg Balaenoptera skeleton 



