58 
Figures. Cadoceraa brooksi sp. nov.; C. caiostoma; and C. sc/iwidfi; widths of umbilicus 
and thicknesses of whorls expressed as fractions of the diameter. Umbilicus 
of C. brooksi, holotjT>e, shown by a solid line marked U; thickness of C. brooksi, 
holotype, by a solid line marked T; umbilicus of Harrison Lake specimens oi 
C. colostoma, by a broken line marked U ; thickness of specimens of C. colostoma 
by a broken line marked T; umbilicus of Harrison Lake specimens of C. sch~ 
midti by a dotted line marked U; thickness of specimens of G. sckmidti by a 
dotted fine marked T. 
slightly ellipticoDic periphery. However, these differences are acquired 
only with late maturity so are not to be taken as a basis for separation. 
The genus indicates a late Cardioceratan date : most of the European species 
being in the excavatum zone. 
Anacardioceras perrini sp. nov. 
Plate XVII, figures 1, 2, 3; Plate XXII, figure 1; Figures 4, 5, 6 
Living chamber, one-half whorl. Ornament, striate in the young. 
Becomes heavy enough to be called costate at about 20 mm. diameter. 
