1887.] MR. G. A. BOULENGER ON A NEW GECKO. 339 



distinct calcified milk-teeth, as shown in the accompanying drawing 

 (fig. p. 338). Both above and below they lie in the groove on the outer 

 side between the uncut pm/ and m.', their summits being slightly 

 above the level of these teeth, but yet not projecting above the gum. 

 They are each about 4 millim. in length, the upper one with a conical 

 root and thickened crown about 2 millim. in diametei', while the lower 

 one is slenderer and has a proportionally longer root and smaller 

 crown. 



It is quite evident that these teeth never become functional, but 

 are absorbed long before the animal is old enough to be able to 

 use them, and in all probability they never cut the gum. 



The discovery of milk-teeth in the Koala is of considerable interest 

 when viewed in relation to their comparatively long persistence in 

 the Phalangers on the one hand, and their entire absence, so far as 

 is yet known, in the Wombats on the other, the Koala presenting in 

 this, as in so many other characters, an intermediate condition between 

 the two. 



In this connection, however, it may be noted tl>at throughout the 

 Mammalia rootless-toothed animals do not have the same need of 

 a functional milk-dentition as do rooted-toothed ones, owing to the 

 manner in which the ever growing teeth are able to increase in size pari 

 passu with the growth of the animal. No better example of this can 

 be quoted than the case of the allied Rodent genera Cavia and 

 Dasyprocta, the first having rootless premolars, whose milk-teeth 

 are absorbed before birth, and the second having rooted premolars 

 preceded by well-developed and long-persistent milk-teeth. 



The bearing of this rule on our present subject is evident ; for 

 while the entire absence of milk-teeth was quite to be expected in 

 the case of the rootless-toothed Wombats, their extreme state of 

 reduction in the Koala is a most surprising fact, especially as there 

 aie in the latter animal no anterior premolars to make up during 

 youth for the absence of milk-teeth, as there are in the Thylacine, 

 in which a similar reductiou of the milk-dentition has taken place. 



5. On a new Gecko^ of the Genus Chondrodactylus , from the 

 Kalahari Desert. By G. A. Boulengek, F.Z.S. 



[Eeceived March 3, 1887.] 



Mr. J. J. Weir, F.Z.S. , has handed over to me two small Lizards 

 from the Kalahari, to be presented to the Natural History Museum 

 in case they should prove of interest. Although unfoitunately in 

 a dry state, having been pinned in an insect- box, they are in 

 comparatively good condition. One belongs to the well-known 

 Eremias lugiibris. Smith, the other represents a new Gecko of the 

 genus Chondrodactylus, Peters, of which a single species was known, 

 C. avgulifer, Peters, also from South Africa. The discovery fa 

 second species is therefore of great interest, and I have much pleasure 

 in connecting with it the name of Mr. Weir. 



