94 ESCHRICHT AND REINHARDT 



The petrous bone in the Greenland whale (as m Avhalebone-whales, generally speaking) is so 

 exceedingly closely wedged in between the surrounding bones of the skull, that it can hardly in any 

 case be separated from them, at least not in a full-grown cranium, without considerable injury 

 either to itself or to the surrounding parts. Again, the tympanic so firmly coalesces with the 

 petrous bone that it can never be loosened from it by the decomposition of the soft parts ; 

 but the firm union between these two osseous portions depends on two processes of bone 

 so thin that the tympanic may very easily be broken off, whe)-f»fore it is very frequently found 

 in museums in a more or less injured state. In half- or fall-grown right-whales these bones 

 are very easily to be distinguished from those of the rorquals, especially by their being almost 

 as broad as long, whereas those of all the rorquals are perceptibly longer, those of the fin- 

 whales even much longer, than broad. In very young specimens this distinguishing mark, 

 and in a still greater degree all the other characters that may be taken from their form, are but 

 slightly developed. We have hitherto been unable to institute a comparison between the 

 tympanic bones of the Greenland whale and those of the remaining right-whales in full-grown 

 specimens. 



In order to show the internal concealed parts of the skull of the Greenland whale, its right half 

 has been figured from the inside from the same forty-seven and a half feet long specimen on 

 the fifth plate. In dividing it with the saw the cut on the Avhole went vertically through the 

 middle line, deviating, however, a little to the left behind, so that in the figure the left lateral 

 surface (e — v'') of the nasal septum covers the right nasal cavity. By this we have gained the 

 advantage that the vomer, which is almost invisible on the surface, appears in our figure from 

 several sides. ^ 



The cerebral cavity (J), so extraordinarily small, comparatively speaking, will be seen 

 behind, together with the occipital foramen (oo — oo), which is displaced entirely on to the 

 upper surface of the skull ; in front we see the immensely thick mass of bone, into which the 

 anterior wall of the above-mentioned cavity has been changed by the coalescence of the 

 occipital {squama occipitalis), the interparietal, the frontals, the ethmoid and the nasal bones. 

 In the vertical longitudinal section of this bony mass it is impossible to distinguish the 

 limits of each of these single bones. It is only according to an arbitrary judgment that we 

 have designated the share of the occipital with the letter o, that of the frontals with/, that of 

 the nasals with 71, and that of the ethmoid with e. Just as the ethmoid in its ossified state 

 coalesces with the frontals, so it will further be seen in the interior of the nasal cavity to be 

 immediately connected with the turbinated bones (c), also perfectly ossified, and the hindmost 

 part of the cartilaginous lining of the nasal cavity, as far as that, too, is ossified {m°). The 

 unossified part of the cartilaginous primordial cranium has disappeared during the maceration, 

 so that not only that surface of the superior maxillary (m^), and of the intermaxillary («), which 

 form the front part of the anterior walls of the nose, and in their natural condition have a carti- 



■" It was necessary to saw through the cranium, as, undivided, it could not be taken through any 

 of the doors of the museum. But the specimen was by no means deteriorated by this proceeding, as 

 we succeeded in having it fitted up in such a way that its two halves, by a special mechanism, may be 

 screwed quite closely together. As an object of study, it has, indeed, gained much, for by the same 

 mechanism the two halves may easily be screwed away from each other, so that all the parts situated 

 along the mesial line can be seen as represented in the figure described above. 



