Bull. U. S. F. C. 1899. (To face page 104.) 
Plate 21 . 
Fig. 37. Monostyla bulla Gosse. Dorsal view. (X 480.) 
p ig. 38. Monostyla bulla Gosse. Side view. (X 480.) 
Fig. 39. Monostyla bulla Gosse. Anteiior margin of lorica in re- 
traction, showing notches in dorsal and ventral plates of 
the lorica. d, Dorsal notch ; v , ventral notch. 
Fig. 40. Monostyla quadridentita Ehr. Dorsal view. 
Fig. 41. Monostyla Junaris Ehr. Ventral view, retracted. 
(X 315.) 
