The first question that arises in the attempt to analyse so complex a grouping on a strange member like the foot of a _loris_ is this--what is the primary function subserved by the ridges and their mode of arrangement, and what may be their secondary uses? In the book referred to I have maintained throughout, in opposition to Mrs. Wilder Harris and others such as Dr. Hepburn, that the sense of touch is the primary, and prevention of slipping the secondary adaptation secured by the ridges. If this be true (and I know it is _sub judice_) there is a very clear reason why the ridges should be longitudinal on the tips of the digits on account of the better discrimination of small objects secured by this arrangement, though it does not well assist the _loris_ to avoid slipping. On D 1, as mentioned, the non-slipping effect is secured by its ridges, and this digit is necessarily less employed for discrimination than support. On the other hand the sloping arrangement on the rest of the segments of D 3, 4, 5 is decidedly less effective in preventing slipping than a transverse arrangement would have been. I think I am justified in saying that too much has been made of this secondary effect of the ridges in the prevention of slipping. I know that the string wound round the handle of a cricket bat is very effective for its purpose, but one can also understand that a casual strand wound here and there on the handle as the ridges are on a _hedgehog’s_ and _squirrel’s_ hand and foot would be of little use for the purpose. On the other hand if the view may be entertained that on the palm and sole of _hedgehog_, _squirrel_, _loris_ and man, we have written in rows of papillary ridges and their modes of arrangement a register of long-continued flexion of hand and foot in flexion and correlated actions, we find the facts of these and numerous other Primates agree in a remarkable manner with the hypothesis; whereas the exclusive non-slipping rival has many awkward facts to explain, or disregard. Further as one has always to bear in mind the Mendelian analysis it should be observed that the extreme variability, within certain limits, of the arrangements of papillary ridges throughout the Primates renders the hypothesis of unit-characters segregated, according to Mendelian laws, wholly inapplicable to the _manner of their arrangement_ even though perhaps not so to the _existence_ of papillary ridges. [Illustration: Fig. 62. Hedgehog--right foot.] [Illustration: Fig. 62A. Hedgehog--right hand.] [Illustration: Fig. 63. Common squirrel--left foot.]