PLATE XX. 



PfiOETUS ^NGUSTIFRONS. 



1'age 91. 

 See Plate 22. 

 Fig. 1. A portion of the cephalon, showing the glabella. The crust is mostly broken away, and the base 

 of the glabella is made too wide in the drawing. 

 Schoharie grit. Albany eourity. 

 Pig. 2. The pygidium. The drawing fails to represent the faint grooves on the pleural annula.tions. 



Schoharie grit. Albany county. 

 Fig. 3. Profile view of a .-mailer pygidium, enlarged to two diameters. 



Schoharie grit. Albany county. 

 Fig. 4. A small pygidium, showing a slight emargination at the posterior extremity. Enlarged to two 



diameters. 

 Fig. 5. Profile view of the same. 



Schoharie grit. Albany county. 



Proetus Conradi. 



Page 89. 

 See Plates 21 and 22. 

 Fig. 9. A pygidium of average size retaining the crust, and enlarged to two diameters. The pleural 

 ampliations are rarely so distinct as in this figure. 

 Schoharie grit. Albany county. 



PkOETUS CANALICULAR S. 

 Page 107. 

 See Plate 23. 

 Fig. 10. The glabella and fixed cheeks enlarged to two diameters. The faint first pair of glabellar fur- 

 rows is not represented in the drawing. 

 Fig. 11. Profile view of the same. 



Corniferous limestone. Falls of the Ohio. 



Proetds CLAUUS. 



Page 104. 

 See Plate 22. 

 Fig. 12. A nearly entire individual, natural size. 

 Fig. 13. Profile view of the same. 



Corniferous limestone. Stafford, Gftnesee county. 

 Fig. 14. A small individual, showing a somewhat broader border and longer cheek-spines. Enlarged to 

 two diameters. 



Corniferous limestone. Stafford, Genesee comity. 



Proetus Hesione. 



Page 93. 

 Fig. 15. The pygidium on which this species was established, showing the greater length and more nu- 

 merous ampliations than in associated species. 

 Fig- 16. Profile view of the same. 



Schoharie grit. Schoharie, Schoharie county. 



