Cover legend: A volume rendered average atlas created with three-dimensional magnetic resonance images of the brains of live C3H mice. The atlas can be used to screen for abnormal brain structure in magnetic resonance images of mutant mice created on the same background strain (yellow = olfactory bulbs, green = ventricles, orange = hippocampus, red = inferior colliculus, blue = cerebellum). For details, see the article by Bock et al. in this issue (pages 4455–4459).