360 Annals of the South. African Museum. 



Noteosaurus. The possession of 6 phalanges in the 5th toe of Noteo- 

 saurus is a striking difference from Mesosaurus, when certainly 

 there are only 4 in the known specimens. 



The phalanges of the 6th toe are slender, and the last one is 

 pretty certainly not clawed, whereas those of the other toes are 

 short and probably had some sort of nail or claw. 



Noteosaurus africanus is a very near ally of Mesosaurus, and is 

 an interesting modification. The increase in number of the 

 phalanges of the 5th toe is exactly comparable to the increase in 

 the number of phalanges in the manus of the Cetacea. It is remark- 

 able to find this modification in one of the oldest known reptiles. 

 The zone in which it occurs is certainly not later than Lower 

 Permian. It may even possibly be Upper Carboniferous. It is 

 further remarkable that only one toe should be thus specialised. 



