112 
PALEONTOLOGY OF NEW YORK. 
border. The specimen is somewhat crushed across the base of the glabella, 
but sufficient is retained to show evidence of strong basal lobes similar to 
those in P. ovifrons, and above these, indications of two pairs of lateral 
furrows. 
The eyes are elongate, relatively narrow, and are closely appressed to the 
glabella. 
The single example has an axial length of 5 mm., a length to the apex of 
the cheek-spines of 9 mm., and a width of 7.5 mm. 
Distribution. Upper Helderberg group. In the decomposed Corniferous chert, 
at North Cayuga, Province of Ontario. 
PrOETUS [?] PLANIMARGINATUS. 
PLATE xxm, PIG. 12 
Proetus planimargmatus, Meek. Proc. Acad. Nat. Sci. Phila., p. 89. 1871. 
Proetus planhiiarginatus, Meek. Palaeontology of Ohio, vol. i, p. 233; pi. xxiii, figs 3 a, b. 1873. 
Pygidium semi-elliptical in outline; length to width as 3 to 5. Surface de¬ 
pressed-convex on the sides, elevated along the axis. Border moderately 
broad, flat and sulcate near the edge. 
The axis, on the anterior margin, has about one-fourth the width of the 
shield, and tapers evenly to a blunt extremity considerably within the poste¬ 
rior margin. It bears ten distinct, and traces of two or three indistinct 
annulations; these are transverse over the median area, slightly angulated 
and inclined posteriorly toward the margins. 
The pleurce each bear nine low, narrow annulations, separated by broad, 
shallow sulci, and each annulation is sulcate upon its summit for its entire 
length. The annulations become obsolete toward the posterior extremity, 
leaving the post-axial area smooth. 
The type specimen of the species is a smooth cast of the lower surface, 
and from Mr. Meek’s observations upon other specimens, the dorsal surface 
appears to have been devoid of ornamentation. 
Dimensions of the original; length 15 mm., width 25 mm. 
