38 1*P1\ KKPOUT OF rUOGKKSS. JAMKS HALL. 



Fig. T). An enlai"o;pinent, to ten (li;iin«'tei's, to show the 

 change from the acute scales near the margin to 

 sliort and more rounded forms. 



Fig. 6. An enlargement from rlie middle of a segment, 

 showing the minute imbricating scales along the 

 anterior portion and large, triangular scales on the 

 middle and lower portion. The figure represents 

 also the posterior and anterior portions of the adja- 

 cent segments. 



Fig. 7. An enlargement of the test where it is ornamented 

 with narrow, triangular scales. 



Fig. 8. Enlargement showing small and large rounded im- 

 bricating scales. 



Fig. 9. A small carapace showing the characteristic elon- 

 gate form of this part of the animal. 



Fig. 10. The caudal sjDine of a small individual. 



Fig. 11. A fragment of shale preserving two detached lat- 

 eral processes of the segments, enlarged to two di- 

 ameters. 



EURYPTERUS STYLUS. 



Page 3.'^.. 



Figs. 12, 13. Two carapaces referred to this species, showing 



their form and ornamentation. 

 Figs. 14, 15. Two individuals of this species, showing the 



broad form of the body and the strong telson. 



Undetermined j-ragmknts. 



Fig. 16. A fragment of shale preserving several fragments 

 of somites of undetermined specific relations. 



Fig. 17. An obscure fragment, i:)ossibly a portion of an 

 ectognath. 



El^RYPTEKUS PENNSYLVANICUS. 



Page 31. 



Fig. 18. A view of the carapace described, showing its 

 broad form, produced posterior angles and the ar- 

 rangement of the nodes on the surface. 



