OF THK I'KLVCOS.vrRlAN GENUS DIMETRODON. 29 



Description of Plates. 



Plate 1. 

 Fig. 1. Kight side nf skull of Diuulrmlun sp. near incisivua, Cope. Specimeu lOOl. 



Fig. I«. Explanation. /., frontal ; J«., jugal ; mx., maxillary ; «., nasal ; orb., orbit ; p., parietal ; pif., posttron- 

 tal ; prf., prefrontal ; pi., parietal foramen ;/<«/., pros-iuamosiil : q., quadrate ; qf., quadrate foramen ; qj., quadrato-jugal. 



Plate II. 



•Fig. 1. Left side of skull of Dbiutwtlun gigas, Cope. Specimen 1002. 

 Fig. la. Explanation. Lettering as in Fig. la, PI. I. pmx., premaxillary ; sm., gepto-raaxillary ; /?. lachrymal ; 

 pt., pterygoid. 



Plate III. 



Fig. 1. Inner side of the left side of the lower jaw of skull shown in I'l. I. 

 Fig. 2. Outer side of right side of the jaw of same specimen. 



Figs. In and 2ri. Explanation, art., articular ; atig., angular ; dent., deutary ; pre-art., pre articular, sp., splenial ; 

 ». ang., surangular. 



Plate IV. 



Fig. 1. Skull of Dimetrodon gigan with the left side removed showing the bones of the median axis. Specimen 1002. 



Fig. la. Explanation, bo., hasi-oocipital ; cp., epipterygoid ; mx., maxillary of right side ; »., nasal ; pv., pre- 

 vomer, pt., verticil plates of the pterygoids ; ;)/., palatine ; pas. parasphenoid ; pt., pterygoid ; ;;/., prefrontal ; pmx., pre- 

 maxillary ; sill., septo-maxillary ; v., ethmoid. 



Plate V. 



Fig. 1. Inner side of the quadrate region of specimen 1001. pt., posterior end of pterygoid, q., quadrate ; qj., 



quadrato-jugal ; qf., quadrate foramen. 



Fig. 2. Posterior view of the occipital region of specimen 1, Dinulroduii incisivus. 



Fig. 3. Lower view of the same. 



Fig. 4. Lower view of the basi-sphenoid of the same speo^men. 



Fig. 5. Lateral view of the same. 



Fig. 6. Lateral view of the pterygoid of the same specimen. 



Fig. 7. Lower view of the pterygoid of the same. 



Plate VI. 

 Fig. 1. Top of the skull of specimen 1001. 

 Fig. la. Explanation. Lettering as in PI. I., Fig. la. 

 Fig. 2. Restoration of the skull of Dimetrodon gigas. Lettering as in PI. I. 



Plate VII. 



Fig. 1. Restoration of the palate of Dimetrodon gigas. Specimen 1002. 

 Fig. 2. Restoration of the median section of the same skull. 



Fig. 3. Restoration of the posterior view of the same skull. Lettering of all aain previous figures, eth., ethmoid; 

 pii., paroccipital. The arrow of Fig. 2 shows the course of the nares. 



