94 Transactions of the Royal Society of South Africa. 
The asymmetry and other variation met with amongst the individuals of 
a newly-born litter may conceivably be the result of inequalities of nutrition 
during the prenatal period, but most probably it arises from true germinal 
variation : the food factor certainly seems to be of no importance during the 
postnatal period, for the range of variation in the pectinal teeth of newly- 
hatched young seems to be practically the same as that exhibited by a series 
of adults collected in the same neighbourhood. Assuming the truth of this 
inference, as long as the members of the same family present such germinal 
variations it is clear that the local race, or "little species," composed of 
many families, cannot be regarded as a " finely cut " unit : such mathe- 
matical units might perhaps be bred out by careful selection in a laboratory, 
but they do not seem to occur naturally amongst scorpions. Of course we 
might arbitrarily divide the specimens of the same species taken together 
in a limited area into so many sets, the members of each set agreeing 
together entirely in respect to any one variable character, but such sets 
would have no natural value unless they should happen to completely 
coincide with the sets constituted on the basis of some other character. 
Turning to other genera, we cannot fail to be greatly impressed by the 
wide variability of many species. Forms which hitherto have been regarded 
as quite distinct are now known to be completely connected by intermediates. 
In the genus Opisthophthalmus, for instance, I do not hesitate to unite 
under one specific name the Transvaal species 0. ]^ugnax Thorell with the 
0. latimanus Koch of the Eastern Province : probably it will eventually be 
found that 0. capensis Herbst and 0. granifrons Poc. are only geographical 
races of the same thing. The species 0. austerus Karsch, which seemed to 
Dr. Purcell a very distinct form, without near relationship, is now seen to 
be closely connected with latimanus Koch. There can be little doubt but 
that in this genus there exists a great number of local units, some of which 
pass insensibly into each other; whether the small units are naturally 
aggregated into larger ones possessing the definiteness of species is not so 
obvious. Nevertheless there are some facts which seem to me to indicate 
clearly that such major units do exist. When two forms which differ 
appreciably in structure can live together in precisely the same environments 
without showing any indication of interbreeding, we are surely justified in 
regarding them as distinct entities. Such instances are known to me, but 
are not common in the genus Opisthophthalmus. It occurs in the case of the 
allied species 0. harrooensis Purcell and 0. aiisterus Karsch ; 0. latimanus 
Koch and nitidiceps Poc. occur together in the same environment at Alice- 
dale, and apparently latimanus extends over the whole area occupied by 
nitidiceps. In the genus Parabuthus, Dr. Purcell has remarked that no less 
than six distinct species are to be found living side by side in Bushmanland : 
instances in the genus Opisthophthalmus are given in Dr. Purcell's introduc- 
