232 
• 
Transactions of the Boyal Society of South Africa. 
Explanation of Table. 
1. Leiig-th of body from snout to vent (in millimetres). 2. Length of cleft of 
closed eye. 3. Diameter of ear-opening. 4. Toes (long and slender x ; short and 
thick 0). 5. Longest toe. 6. Fifth toe extending as far as the first x ; fifth not 
extending as far as the first 0. 7. Length of tibia. 8. Length of head. 9. Length 
of foot. 10. Dorsal scaling (A = like annata, D = distanti, N = normal.). 11. 
Ventral scaling (keeled x ; smooth 0). 12. Scales on upper surface of tibia (equal 
X ; unequal 0). 
Yet most of the differences pointed out in the above synopsis are not to 
be wholly discarded, as they apply to the ensemble of the lizards when 
numbers from one district or locality are brought together, and most of them 
may still be used, in combination, to define varieties, although each lacking 
that amount of fixity which would be requii ed to justify specific distinction 
in the case of A. hrachi/nra, distanti, aculeata and annata. It also became 
evident that the separation of A. ]uicroterolei)is from A. atra, even as a 
variety, could not be upheld. 
Before going further it may be well to explain how we understand the 
conception of species and varieties. 
It is the opinion of the senior author that species are natural entities, 
of which, however, we can only convince ourselves in each case by an appeal 
to ethology and ontogeny.''^ He therefore regards the species in the Linnean 
sense as the real unit of classification. Species may be defined as groups 
morphologically and physiologically limited and stable at the present day. 
From the physiological standpoint we need not fear to include under one 
species forms which show an enormous range of morphological variation. So 
Ave regard man, the dog, the horse as each representing one species, although 
the different forms included under each differ more from each other than do 
many that have proved to be fully entitled to specific rank. It is a common 
fallacy to fancy that such enormous variations occur only in domesticated 
species ; many examples of the contrary could be adduced in the case of 
Reptiles and Batrachians, such as the wall-lizards of Southern Europe, the 
edible frog, etc. There is no measure for specifi.c characters : in every case 
we have to consult Nature, rigid rules cannot be laid down. 
In the case of the European Batrachian fauna, which has been better 
studied from the point of view of ethology and ontogeny than any other 
department of Herpetology, there should be no difficulty in deciding as to 
* As opinions still differ on this " physiological sanction " of species Ave may quote 
Bateson's latest view (1914) : "Whether science will hereafter discover that certain 
groups can by peculiarities in their genetic physiology be declared to have a preroga- 
tive quality, justifying their recognition as species in the old sense, and that the 
differences of others are of such a subordinate degree that they may in contrast be 
termined varieties, further genetic research alone can show. I myself anticipate that 
such a discovery will bo made, but I cannot defend the opinion with positive 
conviction." 
