PLATE XXVIII. 



I'AGK. 



"Fig. 1 . Ptyonms Yinchellianus. T wicb natural size 376 



2. Ptyonivs pectinalUH, Cope. The upper right-hand flgiire, P. Marshii. Natural size 377 



3. Ptyonius Marshii, Cope. Natural size '. 375 



4. H^tyorvvm pectinatics, , Cope. Natural size '. 377 



. 5. Fbyonius ? aerrula, Cope. Natural size ». 379 



6. PtyoTVms pectinatus, Cope. Natural size 377 



