312 
PALEONTOLOGY OF NEW-YORK. 
nearly the same width as the front, and reaching to the base of the eye-tubercles; lateral lobes 
of the glabella oval-ovoid, having their longitudinal axis directed obliquely forward ; oculiform 
tubercles auriform, broader at the base ; transverse furrow broad and well defined, extending 
nearly to the posterior angles of the buckler ; facial suture coming to the base of the buckler 
about half way between the base of the eye and the posterior angle; thorax composed of 
eleven articulations; axis convex, gradually tapering to the posterior extremity • lateral lobes 
with the articulations flat, falcate, a distinct broad groove extending the entire length, and 
terminating in the acute extremity. Pygidium laciniate; axis marked by two narrow articu¬ 
lations above, and a third posterior one which is prominent and very convex in the middle, 
from whence it abruptly slopes downward, becoming confluent with the expanded border; 
lateral lobes composed of three articulations which are much expanded in the middle, but 
contract to acute points below, forming the laciniate margin. Entire surface scabrous, having 
the acute pustulose points directed backwards. 
The under side of the crust shows puncta corresponding to the pustulose elevations on the 
upper side, and the same striated or lamellose surface towards the extremities. The clypeus is 
attached directly below the front of the glabella : it is broadly rounded in front, and obtusely 
bifurcate behind. A little behind the centre it is depressed in the middle; and on each side, 
equidistant from the margin and each other, are two strongly marked depressions, from which 
proceed grooves extending obliquely forwards, and curving round the anterior portion of the 
clypeus. A little outside and behind these depressions are two others, less deep, and com¬ 
municating with the groove just mentioned by a more shallow one. Margin of the clypeus 
striated ; central portion with oblong or angular punctures. 
This species, in an entire condition, is one of the rarest as well as most beautiful trilobites of 
the group, though fragments of the buckler and pygidium are not unfrequently found in the shale. 
It is easily recognized, however, from any. other species, by the peculiar surface marking : the 
form and terminations of the articulations either of the body or tail, and the glabella and other 
portions of the head are equally characteristic. The form alone, of the eyes, is all that can be 
determined; since in all the specimens seen, they are more or less crushed, and the upper 
margin projects beyond the base so that the lateral or vertical portion is broken off, or left 
attached to the matrix. In the larger number of specimens the eye-tubercle is so mutilated that 
it is scarcely to be recognized as that organ, and is not always distinguished from the lobes of 
the glabella. The projecting portion anterior’ to the prominent front of the glabella, appears 
rather to be an expansion of the margin or border which surrounds the front of the buckler; 
and at its edge, and beneath, is striated or lamellose. A partial exfoliation of the crust from 
the upper surface shows beneath it the same striated surface, which, at the base, extends in¬ 
ward nearly as far as the point where the facial suture comes out, and gradually narrows above, 
till at the lateral anterior margins of the glabella it has scarcely a perceptible width ; but from 
this point it again expands, forming the projection in front. The outer extremities of the 
articulations, for more than one-third of their length in the upper part of the body, and one half 
their length in the lower part, are striated, or sharply grooved across in lines continuous with 
