Fig. 1. Skeletal and dental components of the hagfish feeding apparatus. (A) Dorsal view of an unfolded dental plate (oral mucosa removed) from Eptatretus stoutii, including methods for measuring dental plate width and dental plate length. Thick broken vertical line represents the axis about which bilateral folding occurs. Anterior and posterior tooth rows are indicated by blue and red outlined ovals, respectively. 2–3 medial teeth in each row are fused and fusion patterns of these medial teeth vary with species. For example, a M. glutinosa specimen would have two fused medial teeth in the anterior row (Ferholm, 1998). (B) Ventral view of an E. stoutii with the gray box representing the position of the basal plate. The inset shows a schematic of the basal plate in ventral view with the resting position of the dental plate and methods for measuring basal plate length and width. Below is a photograph of a basal plate in dorsal view. ABP, anterior basal plate; MBP, middle basal plate; PBP, posterior basal plate; LB, lateral bar; MB, medial bar. (C) Lateral view of the cranial skeleton of M. glutinosa, including the notochord (NC) and spinal cord (SC). Material highlighted in blue represents the cartilages and teeth of the feeding apparatus. DP, dental plate. Image has been modified from (Cole, 1905).