The same is true for Ariaspis for which Elliott & Swift (2010) showed the presence of a continuous lateral lamina with no notch for the branchial opening and a posterior opening for the
branchial duct. A branchial plate was identified in Listraspis by Denison (1964), however, a review of the original and some additional material indicates that this is a lateral lamina not separated from the rest of the dorsal shield (DKE, pers.
The denticles and denticulate platelets discovered, along with rostral, cephalo-pectoral and lateral scales, give evidence that they come from the anterior part of the body, from the lining of the bucco-pharyngeal and branchial regions (i.e., the mouth and throat, and the
branchial ducts and chambers).