Apart from the lack of a causal argument for introducing the axis in the telencephalon , there is the obvious difficulty that there is a pair of telencephalic vesicles .
A bifid axis is actually implied in these outdated versions .
Apart from the lack of a causal argument for introducing the axis in the telencephalon , there is the obvious difficulty that there is a pair of telencephalic vesicles , so that a bifid axis is actually implied in these outdated versions .