 The gill arches are equipped with rows of parallel 3-to-12-centimetre-long (1.2-to-4.7-inch-long) gill rakers, in life probably attached to the ceratobranchials via soft tissue.On the top of each raker one or two rows of dozens of low "teeth" are present.When there are two rows, they are placed on the edges of the upper surface and separated by a deep trough, itself separated from an internal hollow space by a transverse septum.