PLATE XXIV. 



PAGE 



MACKOCHEILUS ALTONENSE Worthen 1 i;t 



Figs. 1 and 1 n. Opposite views of the spire, natural size. 



PLEUROTOMABIA IOVENSIS Worthen iss 



Fig. 2. Dorsal view of the spire, natural size. 



STHAPAROLLUS SUBUMBILICATUS Worthen !)_> 



Figs. 3 and 3 a. Front and back views, natural size. 



Fig. 3 b. Dorsal view of a larger individual, with a more depressed spire. 



ORTHONEMA CARBONARIUM Worthen U.-, 



Fie. 4 and 4 a. Opposite views of spire, natural size. 



PLECBOTOMARIA MONTEZUMA Worthen i:a; 



Fig. 5. View of lower volution, natural size. 



