Cover illustration. Gas bladders of ray-finned fishes have long been regarded an evolutionary modification of lungs. Critical evidence for this hypothesized homology is whether pulmonary arteries supply the gas bladder as well as the lungs. In this issue of the Journal of Morphology, Longo et al. present a study (pp. 687–703) of the pattern of major arteries supplying lungs and gas bladders in ray finned-fish and lungfish. The cover image shows the 3D-reconstruction of the anterior arteries from a micro-CT scan of a sturgeon (Acipenser transmontanus), including the heart and gills (yellow). Injection with radiopaque barium prior to scanning facilitated visualization of the arterial vasculature (yellow, orange, and light red) and led to the discovery of vestigial pulmonary arteries in sturgeon and their close relatives, paddlefish. Image created in Avizo Fire 7.1 by Mark Riccio and edited by Sarah Longo.