Our ‘excellent egg merchant,’ introduced as the Racer, though a ground snake, is equally at home in a tree, and holds on by its tail with remarkable adroitness, but then the Racer or ‘Pilot snake’ is a true boa also. (The true ‘boa’ is distinguished by its dentition and formation of jaw-bones, the term ‘boa,’ so variously and perplexingly used by some of the older naturalists, being now restricted to certain non-venomous species which possess such anatomical structure.) Lawson’s description of this ‘Racer’ is graphic. ‘The long black Snake frequents the Land altogether, and is the nimblest Creature living. His Bite has no more Venom than a Prick with a Pin. He is the best Mouser that can be; for he leaves not one of that Vermin alive where he comes. He also kills the Rattlesnake wherever he meets him by twisting his Head about the Neck of the Rattlesnake, and whipping him to Death with his Tail. This Whipster, for all his Agility, is so brittle that when he is pursued, and gets his Head into the Hole of a Tree, if anybody gets hold of the other End, he will twist and break himself in the Middle.’ Lawson does not appear to have understood the nature of constrictors. ‘Whipping’ the rattlesnake was probably only the tail lashed in anger, or used in controlling the exceedingly active movements of the captor. As for its ‘breaking itself in halves,’ many exaggerated stories are told by unscientific spectators of the ‘brittleness’ of snakes, the simple explanation being that all are alike irritated and terrified when rendered helpless by their tail being fettered, and may then struggle until they injure themselves. The common blindworm (_Anguis fragilis_) has been seen to so-call ‘break itself in halves;’ but this will be explained in its place (chap. xxv.). This sensitiveness—_sensibility_, one may almost term it—in the tail of snakes has been pointed out by the late Frank Buckland, Dr. Stradling, and others of like practical experience, affording useful information in case of danger. ‘If attacked by a boa constrictor, it is of no use to pull and haul, but catch held of the tip of the tail and unwind him.’ Also, ‘when striking, aim at the tail. The spinal cord there being only thinly covered with bone, it is more easily wounded; and when the spine is broken, the animal is disabled.’[58]