Barchan dunes are solitary crescent dunes formed on a flat, hard ground with limited supplies of sand and vegetation. Transverse dunes are a series of long ridges that are found in areas that have a lot of sand but sparse vegetation.
Transverse dunes are sand dunes formed across the direction of the winds that prevail in a given area. This is the "normal" way dunes form when winds blow sand across open areas. A link can be found...