1895. ] NEW YORK ACADEMY OF SCIENCES. 143 
pressed with two, somewhat oblique furrows; there is a small 
obscure tubercle on the edge of the glabella opposite the ocular 
fillet; the glabella is flatly arched sidewise, bent down behind, 
and is bounded by a distinct dorsal furrow. The fixed cheek is 
rather flat, arched down at the side in front,and also arched 
downward at the back; it bears a thick ocular fillet, which ter- 
minates in a distinct swelling at the dorsal furrow; it has a well 
defined though narrow groove, which descends to the posterior 
marginal furrow inside of the eyelobe ; the eyelobe is continuous 
to the posterior marginal furrow. The occipital ring is depressed 
below the glabella, and is narrow. The posterior fold and fur- 
row also are weak and narrow. The dorsal suture runs forward 
' to the frontal limb, parallel to the axis of the shield, and back- 
ward behind the eyelobe direct to the posterior margin. 
A movable cheek svhich accompanies the centre piece of the 
head of the species, is narrow, moderately arched, and rounded 
at the genal angle. 
Sculpture. The surface is minutely tuberculate. 
Size. -Length of the head-shield 18 mm.; width at the front, 
between the sutures 16 mm., at the eyelobes 23 mm. 
Horizon and locality. Sandstones at the top of Assise 3. 
Scarce. 
This species is distinguished from the others by its upturned 
anterior marginal fold, and by the sharp furrow along the inside 
of the eyelobe. In this and in the tubercle at the side of the 
glabella it resembles genus Avalonia, Walcott. The glabella is 
broader and flatter than that of the two preceding species. 
This species appears to have many points in common with 
Zacanthoides levis found in company with Olenellus Gilberti at 
Highland Range, Nevada*; the form of the glabella, the up- 
turned front margin of the shield, and the sweep of the ocular 
fillet and eyelobe are similar; but our species appears to have a 
direct posterior extension of the suture, which would exclude it 
from Zacanthoides. Mr. Walcott compares Z. levis with Billings’ 
Bathyurellus abruptus only known by asmall head from northern 
Newfoundland +; this species, however, is referred by Mr. 
Billings to the Quebec Group (Ordovician), and so must be of 
much later date than the other two species above named. 
Micmacca (?) PLANA n. sp. Pl. xi., figs. 2 a and 3 b. 
Middle piece of the head-shield subquadrate, depressed, ex- 
cept the glabella, which is only moderately elevated. Front 
*U.S. Geol. Surv., Bull. 30, p. 187. 
+ Paleeoz. Foss., vol. i., p. 263. 
