10^ Transactions of the Royal Society of South Africa. 
Conclusions. 
The genus Brookesia approximates to the normal lacertilian type in so 
many respects that we may safely regard it (and Bha^npholeon probably) 
as the most generalized of living Chamaeleons. The puniilus section is in 
several respects the least specialized division of the large genus Chamaeleon 
and the dilejois section is the most advanced of the whole family. Mr. 
Beddard comments on his lung investigations as follows : "The simplicity of 
structure which is often associated with small sized forms as compared 
with their allies of larger size is well seen in the two small species of 
Chamaeleons, viz., G. puinilus and C. tacniohronchus where the lungs have 
no diverticula and the intestinal tract is nearly straight." This is only 
partially correct : it is certainly correct that all the largest species belong 
to the advanced group, but some of the Malagasy species {e.g., C. lateralis) 
which are smaller than C. immilus or C. ventralis, must also be included 
amongst the most specialized forms. Although Mr. Beddard does not thus 
explain the facts, some might infer that smallness of size is accompanied to 
some extent by degradation in structure giving a false appearance of sim- 
plicity ; and while admitting the possibility of such degradation in Brookesia 
and C. immihis with respect to some characters {e.g., the reduction of the 
squamosal and absence of lachrymal), we think it highly improbable that 
this can be the explanation of the simplicity of those types in respect to so 
many characters. Indeed, the fact that the vulgaris and dilepis section 
show in immature specimens some of the characters which belong to the 
adult stage in G. pumilus, Brookesia, or Bhaviyholeon, whilst, on the other 
hand, G. ventralis, at any rate, does not pass through a stage reminiscent of 
the higher types in its young, is decidedly against that view.* Further, 
our opinion with regard to the primitive nature of Brookesia is in some 
degree supported, we think, by the fact that Madagascar is known to be 
the home of primitive animals in various groups (cf. especially the 
primitive Colubrine snakes of that island) ; however, we do not desire to 
lay stress on this argument, as it cannot be said that the whole Malagasy 
fauna is primitive. 
It is important to note that the one or two widespreading Mediter- 
ranean and Indian species are included amongst the most advanced section 
which, moreover, has its headquarters in Africa. We are probably justified 
in assuming therefrom that the extra-Ethiopian species are outliers which 
have spread in comparatively recent times to the places they now inhabit, and 
there is no reason to suspect that they are relict forms indicating a former 
much wider distribution for the family. On the other hand, Chamaeleon 
* Fully to substantiate this argument, more complete embryological data than is now 
available will be required. By tracing the development of the skull and of the lungs in 
the embryos of Brookesia and various species of Chamaeleon, the problem could in all 
probability be definitely settled. 
