This is a small triumph in more ways than one. First, the authors are exemplars of a tradition that gets more lip service than active imitation -- a tradition that is more British than American -- that of the expert amateur. Second, they can speak seriously about things they take seriously while laughing. They were born naturalists and identical twins. They've hugely enjoyed being both. The stories of reptile and insect collecting are told very personally and illustrate how they've used their twinship to advantage in their school days, in the Army, in their government jobs and as school masters. Perhaps it is this last experience that gives them their expertise in the sort of contagious irreverence calculated to appeal at any reading level. They tell their life story in its most important phase -- their lifelong, dual mono-mania for the collection of small reptiles and insects which they present to the London Zoo. They've had a wonderful time of it, casually tuck in a lot of tips on how to go about it among their anecdotes, and even the most squeamish readers will get the urge to capture it rather than step on it after reading this.