DINICHTHYS, (Neo-Lat.. from Gk. Sauk, deinos, terrible ixeic, ichthys. fish).
A genus of fossil dipnoan fishes of large size belonging in the order Arthrodira, and found in the uppermost Devonian and Lower Carboniferous rocks of North America, and less commonly inn Europe. The body is estimated to have had a length of IS to 18 feet, but few traces of other portions than the heavy armor-plates of the head and anterior part of the trunk have been observed. The general form is similar to that of Coccostens, with which it is quite closely related. The head was often over three feet in width and four or more feet long, and the bones of the skull were heavy plates, well joined to gether to form a solid dorsal head-shield. The eyes were of large size. as indicated by the form of the orbital notches in the margin of the head shield. The dentition, which resembles that of the modern Protopterus, was very formidable. It consisted, in the upper of two large an terior triangular teeth that functioned as in cisors, and two lateral oblong plates with sharp enameled cutting edges. The lower jaws are very strong and have, at their anterior ends, prominent sharp teeth that interlock with those of the upper jaw, and behind these the upper edges of the jaws are hardened by enamel and sharpened to form very efficient smooth or den ticulate cutting edges, that must have engaged with the corresponding sharp edges of the upper jaw in a shear-like motion. The plates of the
neutral surface of the head and those of the anterior part of the trunk resemble the CoT I esponding plates in the genus Coccostens, and there is a betNveen the head-plates and the body-plates.
The larger moniker of these fossils have been found in the l'pper Devonian Cleveland shale of Ohio, from which formation they were originally described by Prof. J. S. Newberry. The hest known species are Dinichthys Hertzeri and Diflichthys lerrelli. Consult : Newberry, "The Palfeozoic Fishes of North America," ilonograph of the f nib d s (i. nhigica Surre y, vol. xvi.
(11 ashington,Isms) ; Dean. I asits, Living and iNk vv York. Dean. to the Anatomy of vie.. in Trails actions el the Fork _lead. my of n nets, xv. vol. ; and vol. xvi. P..1S). See LUNt.ri,n.