256 



MKIMSTH 1 VARIATION. 



[PART i. 



D. viverrinus : right upper m* slightly larger than the left, which 

 is normal. (..'. .M., .'is, </. 



D. maculatus, Tasmania, having a supernumerary molar 

 in left upper jaw, and on both sides in tin- lower jaw. The 

 fourth molar in the upper jaws is increased in size in a remark- 

 able manner < Fig. b'7, B and C). 



This case requires detailed description. In Fig. 67, A, a 

 normal right upper jaw is shewn. It belongs to a specimen 

 consiileralily larger than the abnormal one, but the latter, 

 Mr Thomas tells me, is a good deal smaller than the normal 

 size of the species. In the normal there are two small pre- 

 mol.iis < /,' and j* of Thomas), and behind these, four molars. 

 The molars increase in size from the first to the third, which is 

 by far the largest. Behind the third is the fourth molar, which 

 i- much smaller than the others, having the peculiar flattened 

 form -hewn in the Figure 67, A. 



FIG. 67. A. Right upper jaw of normal Dusyunts maculatus (shewn as far as 

 the canine) for comparison with the variety. (N.B. The latter is considerably 

 smaller.) 



B. Upper jaw of /'. nt,i'-nlntttx. No. 38o. 



C. Lower jaw of the same specimen. 



<>n comparing the abnormal skull with a normal one it is 

 seen that the two pivnmlars and first three molars on each side 

 are unchanged. IVhind the third molar on the right side there 

 is a single tooth; but this, instead of being a thin tooth like 

 normal '', is considerably larger and the longitudinal measure- 

 ni' ni in the line of tile jaw is not very much less than the 

 transverse measurement. In the right upper jaw therefore the 

 iiim/licr of the teeth is unchanged. 



On the left side, behind the third molar, there is a square 

 tooth (/"') of good size, about equal in bulk to half ' , while 

 behind this again there is another tooth, m^, which is a thin 



