Figure 6. 



FLAIE IX.— Continued. 

 Bythocypris cylindrica, (page 48). 



A valve of this species, x 18, m ith the dorsal margin more convex 

 than usual. This feature is slightly exaggerated in the draw- 

 ing. 



Primitia ? (? Beyrichia) parallel a, (page 51). 



Figure 7. This figure is faulty, but with several strokes of a pencil can be 

 made approximately correct. The ends of a perfect valve are 

 a little more obtuse than represented, but with that exception, 

 the outline and the central portion of the figure are correct. 

 What is lacking is a raised border or fold at each end. These 

 may be supplied as follows : One mm. within the posterior 

 (right) margin a heavy line should be drawn, curving slightly 

 less rapidly than this end is shown to curve. A similar line 

 should be drawn 1.5 mm. within the anterior margin, its curve 

 to correspond with that of the anterior end of the figure. 

 These lines must intersect the dorsal and ventral margins and, 

 if correctly drawn, should cause the ends of the figure to appear 

 elevated and separated from the suboval body of the valve by 

 deep sulci. 



Figure la. Sectional view of central portion of the valve, x 18, showing its 

 convexity and the depth of the sulcus. 



Primitia lativia, (page 50). 



Figure 8. A left valve, x 18. 



Figure 8a. Sectional view of the same, x 18, showing its convexity and depth 

 of sulcus. 



Eurychilina reticulata, (page 52). 



Figure 9. Perfect right valve of this species, x 18, from the Trenton shales 

 at Minneapolis, Minn. 



Figure 9o. Two sections of difl'erent valves of the same, x 18. The lower end 

 of these sections should have been made to bifurcate, and the 

 concave line extended a little further inward. 



Eurychilina Manitobensis. (page 53). 



Figure 10. Left valve of this species, x 18. The border at the upper left 

 hand margin is represented as being decumbent, while this 

 edge is slightly elevated iu the specimen. 



Figure 10a. Section of the same, showing its convexity !^and the shape of the 

 marginal hollow- 



