ILLUSTRATIONS. 



Plates. 

 I. Semionotus agassiziiX^. C. Redfield). Trias ; Sunderland, 

 Massachusetts. Type of Newberry's so-called Isehypter. 

 us mars hi. X^ 



II. Semionotus agassizii {yj. C. Redfield). Trias; Sunderland, 

 Massachusetts. Head and anterior portion of trunk- 

 XI 



III. Semionotus fultus (Agassiz). Trias; Boonton, New Jersey. 



Figured specimen. X| 



IV. Semionotus micropterus (Newberry). Trias; Durham, Con- 



necticut. X| 



V. Semionotus elegans (Newberry). Trias; Boonton, New Jer- 

 sey. Figured specimen. X^ 



VI. Semionotus nilssoni Agassiz. Rhaetic ; Hoegenaes, Sweden. 

 Head portion of holotype, showing cranial plates and 

 dentition. X^- 



VII. Ptycholepis marshi Newberry. Trias ; Durham, Connecticut. 



VIII. Ptycholepis marshi Newberry. Trias ; Durham, Connecticut. 

 Showing dorsal aspect of vertically compressed cranium. 

 XI 



IX. Catopterus gracilis J. H. Redfield. Trias ; near Middletown, 

 Connecticut. Cotype. X| 



X. Catopterus gracilis J. H. Redfield. Trias ( Posterior shale ) ; 

 Durham, Connecticut. Scales appearing whitish by 

 reason of mineral replacement. Xj 



XI. Catopterus gracilis J. H. Redfield. Trias ; Durham, Connect- 

 icut. Xl 



