Plate 9 



Eoharpes ottawensis (Billings) 



Page 116 



Fig. i Specimen, somewhat laterally compressed. Natural size. 

 Snake Hill beds. Snake hill, Saratoga county, N. Y. 



Proetus undulostriatus (Hall) 

 Page 117 



Fig. 2 Hall's type, x 3. From squeeze. 

 Fig. 3 Cranidium. x 3. 



Snake Hill beds. Snake hill, Saratoga county, N. Y. 



Acidaspis crossota (Locke) 



Page 119 



Fig. 4 Free cheek, x 6. 

 Fig. 5 Cranidium. x 5. 



Indian Ladder beds. Indian Ladder, Albany county, N. Y. 



Calymmene senaria Conrad var. 



Page 120 

 Fig. 6 Young, fairly complete individual, showing the medial tubercle on 



the occipital ring. Natural size. 

 Fig. 7 Protaspis stage, x 20. 

 Fig. 8 Nepionic stage, x 20. 

 Fig. 9 Early neanic stage, showing the appearance of the glabellar lobes 



in the glabellar furrows, x 20. 

 Fig. 10 Mature individual, much flattened. Natural size. 



Canajoharie shale. Canajoharie and Sprakers (figure 10), 

 Montgomery county, N. Y. 



Ulrichia ? bivertex Ulrich 



Page 120 



Fig. ii Right valve, showing normal expression of form, x 20. 

 Fig. 12 A left valve with slightly different aspect, x 20. 



Canajoharie shale. Canajoharie, Montgomery county, N. Y. 



Primitiella unicornis Ulrich var. 



Page 121 

 Fig. 13, 14 Two right valves showing the elongate form and the lateral 



node, x 20. 

 Canajoharie shale. Canajoharie, Montgomery county, N. Y. 



Ceratopsis chambersi (Miller) var. 



Page 121 



Fig. 15 Left valve showing the average expression of the variety. 

 Indian Ladder beds. Indian Ladder, Albany, N. Y. 



141 



