PLATE I. 



Fig. 1. CANCER BREWERII. Natural size. 1 



Fig. 2. TRIPTERA CLAVATA. 



Two views, magnified to show front and lateral outlines. 1 



Fig. 3. TROPHON PONDEROSUM. Natural size. 2 



Fig. 4. CHRYSODOMTJS RECURVA. Natural size. 3 



Fig. 6. ? METULA R^MONDII. Natural size. 3 



Fig. 6. CLAVELLA GRAVIDA. Natural size. 4 



Fig. 7. C. SINTJATA. Natural size. 5 



Fig. 8. PLEUROTOMA CARPENTERIANA. Natural size. 5 



Fig. 9. P. TRYONIANA. Natural size. 6 



9 a. Restored outline of outer lip, from the lines of growth. 



Fig. in. P. (SuRCtTLA) PERVERSA. Natural size. 6 



Fig. 11. S. VOYI. Natural size. 7 



Fig. 12. CLATHURELLA CONRADIANA. Magnified. 7 



