Beagles are better at ground-scenting (following a trail on the ground) than they are at air-scenting, and for this reason they have been excluded from most mountain rescue teams in favor of collies, which use sight in addition to air-scenting and are more biddable. The long ears and large lips of the beagle probably assist in trapping the scents close to the nose. In the 1850s, Stonehenge recommended a cross between a Beagle and a Scottish Terrier as a retriever. He found the crossbreed to be a good worker, silent and obedient, but it had the drawback that it was small and could barely carry a hare.More recently the trend has been for 'designer dogs' and one of the most popular has been the Beagle/Pug cross known as a Puggle. Some puppies of this cross are less excitable than a Beagle and with a lower exercise requirement, similar to the Pug parent; but many are highly excitable and require vigorous exercise.