400 University Geological Survey of Kansas. 



PLATE LIV. 



Gillicus arcuatus (f) Cope. Caudal fin, slightly under one-half natural size. 



PLATE LV. 



Saurodon xiphirostris Stewart, about three-fifths natural size: pden, pre- 

 dentary; den, dentary; dar, dermarticular ; max, maxilla; pmax, pre- 

 maxilla; eth, ethmoid; fr, frontal; pfr, prefrontal; pa and ptot, pterotic; 

 spot, sphenotic; hm, hyomandibular; qu, quadrate; na, nasal; prop, pre- 

 operculum; op, operculum; pal, palatine; so, sclerotic ring; 1, 2, 3, ver- 

 tebrae. 



PLATE LVI. 



Saurodon ferox Stewart. 



Fig. 1. — Upper and lower jaws, one-half natural size: max, maxilla; pmax, 



premaxilla; den, dentary; pden, predentary; dar, dermarticular. 

 Fig. 2. — A small toothed element, the exact location of which is not known, 



natural size. 

 Fig. 3. — Right quadrate, one-half natural size. 

 Fig. 4. — Ceratohyal, one-half natural size. 

 Fig. 5. — Centra of first anterior vertebra, natural size. 

 Fig. 6. — Glenoid portion of scapula, natural size. 

 Figs, 7, 8. — Portions of pectoral fin-spines. 



PLATE LVII. 



Saurodon ferox Stewart. 



Fig. 1. — One-half natural size: max, maxilla; pma, premaxilla; den, den- 

 tary ; pden, predentary ; dar, dermarticular; auar, autarticular. 

 Figs. 2, 3. — Internal view of right quadrate and hyomandibular. 

 Figs. 4, 5. — Saurodon phlebotomus Cope, external view of right maxilla 

 and mandible. 



PLATE LVIII. 



Figs, la, b. — Premaxillce of Protosphyrcena occidentalis Stewart, natural size. 

 Figs. 2a, b. — Outline and external markings of rostrum of Protosphyrcena ben- 



toniana Stewart; the first natural size, the second one-fourth natural size. 

 Figs. 3a, 6. — Maxilla, premaxilla and dentary of Saurocephalus dentatus 



Stewart, one-half natural size. 

 Figs. 4a, b. — Internal view of maxilla, premaxilla and dentary of same. 



