192 



IOWA GEOLOGICAL SURVEY 



ter of the superficial ornamentation. The suture lines, however, 

 are less undulating than in Coccosteus, the articulation with the 

 abdominal armor is much stronger, the pineal is partly in con- 

 tact with the centrals, and the dentition is characteristically 

 Dinichthyid, with strongly developed vomerine teeth. The an- 

 terior margin of the lower dental plates is developed into a prom- 

 inent beak, and the superior or functional margin is strongly 

 denticulated; the posterior extremity of the splenial is broad 

 and spatulate. The suborbitals are unusually wide and massive, 

 and the rostral seems to have been laterally expanded in front. 

 The dorsomedian bears the usual inferior keel, its terminal proc- 

 ess being given off at a slight distance in advance of the posterior 

 margin. 



Fig. 27. 



Fig. 27 Dinichthys halmodeus (Clarke). Marcellus shale (Erian); New York. Restor- 

 ation oi lieadshield and dorsal armoring of trunk, x J. ADL, anter-odorso-lateral; DM, 

 doreo-median; EO, external occipital; M, marginal; MO, median occipital; P, pineal; PDL, 

 postero-dorso-lateral; R, rostral; SO, suborbital. Original in New York State Museum. 



