1895. ] NEW YORK ACADEMY OF SCIENCES. 141 
The movable cheek is narrow, arched inward at the end, and 
apparently without spine. 
Sculpture. The surface of the test is smooth and shining, but 
under a lens appears to be minutely punctured. At the back of 
the fixed cheeks are faintly marked, radiating and anastomosing 
raised lines. 
Size. Length of the head shield 6 mm.; width 8 mm. 
Horizon and locality. Sandstones of Assise 3 at Hanford 
Brook. Rare. 
This species appears to belong to Walcott’s genus Avalonia 
by its form, size and surface ornamentation. There is a groove 
around the front of the fixed cheek, such as Walcott has de- 
scribed for Avalonia manuelensis ; but in our species the front 
of this groove does not take the place of the ocular fillet, which 
is further back on the cheek. The heavy occipital ring is a con- 
spicuous difference from the Newfoundland species. 
MICMACCA n. gen. 
Under this head the author proposes to describe a group of 
trilobites with large, rather prominent, cylindrical glabella, which 
extends almost to the front of the shield; and with continuous 
eyelobes, and a short, direct posterior extension of the dorsal 
suture. 
In the narrow front area of the head shield and the large 
glabella, they are like Zacanthoides of Walcott, but they have 
not the long outward posterior extension of the dorsal suture ; 
hence the pleurze must have been essentially different. 
In the long eyelobes and the short posterior extension of the 
suture they resemble Ellipsocephalus, but they lack the com- 
paratively wide front area of the middle piece of the head shield 
of that genus, and its smooth glabella, expanded in front; they 
are all trilobites of larger size than any true Ellipsocephalus. 
The genus is named for a tribe of Acadian aborigenes. 
MicmaccA MATTHEVI n. sp. Pl. x., figs. 1 @ and b. 
Middle piece of the head subquadrate. Front margin with a 
narrow flat fold; front area greatly narrowed in front of the 
glabella. Glabella large, cylindrical, slightly enlarged at the 
front, having three pairs of furrows, scarcely perceptible. Oc- 
cipital ring broad, rounded forward at the back, divided from 
the glabella by a distinct furrow; it bears a small tubercle on 
the axial line. The fixed cheeks are tumid, depressed before 
and behind; at the inner posterior corner it extends behind the 
occipital furrow, and thence is arched forward to the eyelobe ; 
