This ‘slit’ is a very important feature in the fang, and is the cause of much trouble in deciding whether a bitten person has been poisoned or not. It is in reality a very small space _near_ the point, where the involution of the fang is incomplete, that is, where it has remained unjoined. This is to permit the emission of the venom. It is not close to the point, which, as Sir S. Baker affirms, is solid. Being solid, it is stronger and sharper, penetrating the skin of the victim more easily, and making way for the venom which in viperine fangs then follows and escapes through the slit into the wound. By this we comprehend how a person may receive a puncture only, or a scratch with this extreme but solid point, but not deep enough for the poison to enter. The space between the lines at _a_ in the next illustration shows where this slit in the fang is found. In the larger fangs it may be readily discerned with the naked eye: under a magnifying glass it is distinguishable in all. It is distinct in the fangs of the young Jararacas now before me, and extends nearly half-way up the fang in these. The examples of fangs here given are all from nature, and as near to the exact size as it is possible to be in delineating objects of such exceeding fineness and delicacy. Excepting the _Xenodon’s_ and the baby viper’s, the others belong to the _Crotalidæ_, whose fangs are mostly distinguishable by a slight double curve or flange. The viperine fang is a continuous curve (see _f_), but in the _Crotalus_ the point curves very slightly back again and downwards.