Your concern comes from everything you have heard about the effects of a non-crawling baby to his development. From not being able to draw or cut in straight lines to having learning disabilities, there's a list of maladies or consequences of not crawling.
If you have a baby who merely skipped crawling, you should not panic. Then, who made crawling the holy grail of proper physical development? It was probably not physicians. Some claim that crawling is paramount for children to learn eye-hand coordination or going up and down steps one foot at a time.
During the first weeks after birth, the baby is stretching from the scrunched position he was in during nine months. Within the first four months, he will start wiggling and moving his feet. The baby's legs appear to be a bit bowed, but that is fine, they'll straighten. By four to six months the baby will discover his feet and play with them and put his toes in his mouth. He might even use them as hands, trying to reach stuff with them.
Starting at around 7 months, babies are able to get up on all fours and start to rock back and forth. This signals that he is ready to start moving. In most cases, this will be done through crawling. However, of course, some babies will find other ways of locomotion that they find comfortable, for example by scooting on their bum.
Some babies crawl and others shuffle, roll, or wiggle and this has more to do with their temperament than anything else. Some babies are laid back while others are more driven. As long as your baby meets their other development milestones such as pulling to stand, walk aided by furniture, and use their hands properly, there is nothing to stress over.