76 ARKIV FÖR ZOOLOGI. BAND 1. 



niaxillary as on the palatine bones at their junction. But 

 it has even gone so far as to a change of place, as this niolar 

 in earlier stages is rooted, not on the niaxillary, but on the 

 palatine, although near the suture as may be seen on fig. 3. 

 This is, however, surely a secondary feature. In V. salvator 

 the teeth are confined to the maxillary and premaxillary 

 not reaching the palatine. From this description of the skull 

 and the dentition of the adult Varanus salvator it seems 

 perfectly evident that this lizard has been subjected to a 

 thorough metamorphosis, making itself apparent in almost 

 every structural detail of the skull when that is compared 

 with those of other typical Varani. No doubt can be enter- 

 tained that this change which has been eifected stånds in 

 connection with, and has been influenced by, a change of diet 

 to which it may be regarded as an adaptation. 



The interest connected with this adaptation is still more 

 increased by the remarkable fact that the phylogenetic de- 

 velopment is so very plainly repeated in the postembryonal 

 development of each individual. It has already been alluded 

 to above that the young Varanus niloticns* has acutely point- 

 ed teeth of a conical and somewhat recurved shape. It has 

 also been mentioned that the manclible in this early stage 

 is rather slender, concave on the inside, less curved than in 

 the adult and thus, on the whole, resembling that of V. sal- 

 vator. The likeness with this latter extends also in a remark- 

 able degree, not only to the shape of the premaxillary ante- 

 riorky, as noted above, but also to the structure of the palate 

 (conf. fig 5). The basipterygoid-processes of the sphenoid 

 have in this young V. niloticus about the same direction as 

 in V. salvator (conf. above). In consequence hereof the me- 

 dian interspace between the pterygoiäea is comparatively 

 very wide. This is elucidated by the fig. 5 and the statement 

 that on the skull of the young, with a total basal length of 

 o 2 mm., the widest interspace between the pterygoidea is not 

 less than 5Vs mm. while the corresponding measurement in 

 the adult skull (about 136 mm. in length) is not quite 10 

 mm. That is, in other words, in the adult, the skull of 

 which is more than four times as long as that of the young, 

 the interpterygoidal space is not even twice as large as in 



* The specimen used for comparison is as well as the adult one received 

 from Cameroon through my friend Mr. Gr. Linnell. 



