36 



Plate III 



All figures are magnified thirty diameters. 



Page 



Fig. 1. Heterotrypa simplex. Tangential section 22 



Fig. 2. Heterotrypa simplex maculosa. Tangential section 23 



Fig. 3. Homotrypa creditensis. Tangential section 24 



Fig. 4. Homotrypa creditensis. Vertical section 24 



Fig. 5. Homotrypa streetsvillensis. Tangential section 24 



Fig. 6. Homotrypa streetsvillensis. Vertical section 24 



Fig. 7. Homotrypella hospitalis. Tangential section 25 



Fig. 8. Homotrypella hospitalis. Vertical section 25 



