GIK/EyllPEDZJk.. 
BALANID.Z;. 
P R 0 T 0 B A L A N U S , n. g. (R. P. Whitfield). 
PrOTOBALANUS HaMILTONENSIS, 11. sp. (r. p. w.) 
PLATE XXXVI, FIG. 23. 
Shell small, ovate in general outline, narrowing toward the carinal extremity; 
surface depressed-convex, most elevated at the apex of the carina; composed 
of twelve peripheral plates. 
Carina sub-semicircular in peripheral outline, conspicuously elevated to 
an obtuse apex, which lies just within the proximal margin of the plate; 
regularly sloping on the anterior surface, but slightly incurving or concave 
upon the sides. 
Rostrum short, posterior margin broadly curving, apex scarcely elevated. 
The lateralia, which are regularly disposed in five pairs, are symmetrical, 
and of the same general elongate, triangular form and of nearly the same 
size, the anterior members being somewhat the larger. The apices of these 
plates, as far as preserved, are slightly elevated and elongated in a short 
ridge toward the axis of the shell. All these plates are marked by low, 
radiating ridges, which become obsolete before reaching the apex. Of these, 
twelve may be counted upon the carina and six or eight upon the rostrum; 
on the lateralia they vary in number from four to seven. The radial areas 
are conspicuous and, as far as can be discerned, smooth. A portion of the 
