The proliferation of scientific texts and their rapidly escalating costs demands of an author some justification for the production of yet another specialised volume; particularly one that treats of a relatively obscure group of animal- the Cyclostomes-whose significance is little appreciated outside the circle of professional biologists. Yet, within the zoological literature this group of vertebrates has always commanded a degree of attention, quite dispropor tionate to the comparatively small numbers of species involved or their economic importance. This special interest stems in the main...