A treatise on zoology . separate pineal plate, and the frontalsare widely separated by the median occipital which meets the ethmoid. Family Macropetalichthyidae. Macroiyetalichthys, Norm, and Owen;Devonian, N. America and Europe. (1 Astcrosteus, Newb.; Devonian, ) Order 2. ARTHRODIRA. The cranial shield is movably jointed with the cuirass of thetrunk. The centrals (parietals) touch in the middle line, separ-ating, as a rule, a pineal from the median occipital plate. Super-ficial grooves indicate the position of the lateral-line canals. Sub-Order 1. ARTHROTHORACI. The two joints betwe
A treatise on zoology . separate pineal plate, and the frontalsare widely separated by the median occipital which meets the ethmoid. Family Macropetalichthyidae. Macroiyetalichthys, Norm, and Owen;Devonian, N. America and Europe. (1 Astcrosteus, Newb.; Devonian, ) Order 2. ARTHRODIRA. The cranial shield is movably jointed with the cuirass of thetrunk. The centrals (parietals) touch in the middle line, separ-ating, as a rule, a pineal from the median occipital plate. Super-ficial grooves indicate the position of the lateral-line canals. Sub-Order 1. ARTHROTHORACI. The two joints between the shields are typically in correlation with the powerful dentition there is generally a con-siderable space be-tween the twodorsal shieldsabove, allowingthe cranial shieldto be uplifted ; thelower jaw appearsto have but littleplay, being closelyfollowed by theventral plates. Theorbits were boundbehind and belowby a maxilla (sub-orbital). Except in the Coccosteidae, the preorbitals do not Coccosfeus biclcensis, v. , pectoral spine ; i:: Fio. 2iOA. Fiestoratioii of head ami trunk sliieMs, ventral shield. (After Jaekel.) COCCOS TEOMORPHI 263 Family Coccosteidae. The preoibitals (frontals) meet behind thepineal. The teeth are conical and of moderate size. The statementthat they extend on to the symphysis is probably erroneous (Jaekel[244]). In some the ventral shield is produced at each side into aprocess bearing a spine (Traqiiair [459]), whicli in others may be longand movable (Fig. 231). Goccosteus, Ag., Brachydirus, v. Koen; Devonian, Europe. Phlyc-taenaspis, Traq. ; Devonian, Europe and N. America. Acanthasjns,PhoUdosteus, Jaekel ; Devonian, Europe. Family Selexosteidae. The mandibular bones bear a row ofconical teeth along the anterior and the symphysial edge (?). The cranialshield has no orbital notches, and twodiverging posterior wings (Fig. 233). Selenosteus, Dean, Diplogiiathiis,Newb. ; Cleveland shale, N. America. Family Dinichthy
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