Genus Agnostus.— Vogdes. 389 
increases in width going backwards as far as the posterior lateral 
angles, where it is as wide as the lateral lobe of the pygidium, 
but narrows again towards the extremity of the pygidium. The 
limb increases in width from the front as far as the lateral spines, 
behind which it is constricted; at the anterior end it is angulated 
towards the axis, in the rear third broadly rounded. 
Locality. St. John group, Portland and at Hanford brook, St. Mar- 
tin’s. 
The species differs but slightly from Agnostus fullax var. ferox Tullb. 
from the Scandinavian formation at Andrarum with Paradoxides tessini. 
AGNOSTUS VIR var. concinnus Matthew, 1885. Plate rx, fig. 13. 
This variety varies but slightly from Agnostus vir. 
DIKELOCEPHALUS ZONE. 
Section LONGIFRONTES. 
AGNOSTUS AMERICANUS Billings, 1860. 
Syn. Agnostus richmondensis Walcott. Plate 1x, figs. 5 and 11. 
Diagnosis —Head oblong, semi-oval, rather strongly convex, 
most elevated at the posterior quarter of the length, thence de- 
scending with a depressed convex slope in all directions to the 
sides and front. Limb very narrow. The glabella is elongate 
oval, width + that of the whole head, length rather more than 4 
the length of the head. It has two transverse furrows which 
completely or partially divide it into three lobes. The anterior fur- 
row extends all across at $ or a little moreof the length from the 
front. The posterior furrow is interrupted in the middle, and is 
only distinctly seen on each side, penetrating 4 the width, while 
its position is a little in advance of the posterior third of the 
length of the glabella. The space between the two inner extrem- 
ities of the posterior furrows is occupied by a low conical tuber- 
cle, with the apex directed backwards. Basal lobes small and 
triangular. Dorsal groove distinct. Cheeks divided in front of 
the glabella by a furrow. The surface is ornamented by from 15 
to 20 irregular, slightly impressed radiating rugose strie. The 
pygidium is striated like the head. The axis has three lobes with 
an elongated median tubercle, extending across the anterior and 
middle lobes; the posterior lobe is equal in size to the other lobes. 
Locality. Point Levis, Quebec. 
This species approaches A. trésectus Salter, which occurs at Andrarum, 
Sweden with the genus Peltura. 
