S6 FIFTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



or two indistinct ones which are parallel to the axis. The t. 

 beyond the axis is flattened and spreading, concave on thu 

 posterior margin, and the angles slightly produced in flattened 

 spiniform processes. Surface granulose. 



This species differs from the D. selenurus, in the form and proportions of 

 the head ; the prolongation of the posterior angles of the border of the 

 buckler, which reaches sometimes to the fifth articulation of the body ; the 

 greater extension of the fringed border, and the more pointed form in front. 

 The fringe-like appendages are more in number, and are separated by nar- 

 rower spaces : in the caudal shield, there are a larger number of rings on 

 the axis ; but the most distinctive features of this part of the crust are 

 the direction of the ribs in the lateral lobes, and the wide concave posterior 

 margin with scared}^ extended spines. 



In one nearly entire specimen; in two separated heads; and several caudal 

 shields, the above described characters are constant ; and these specimens, 

 with a single exception, are all from the western part of the State. 



Geological formation and locality. In the limestone of the Upper Hel- 

 derberg group : at Williamsville and Clarence-hollow, and at Chittenango, 

 New- York. 



DALMANIA CORONATA ( n. s.). ^^^tvt-v^u --rw^ 



Entire body subelliptical : length and width nearly as two to three, 

 moderately convex; the apex rounded and lising gently above the 

 lateral lobes, which are flattened for more than half their wudth. 

 Head lunate, the length less than half its width. The posterior 

 angles of the border not produced : anterior border ornamented 

 with nine short tooth-like processes; a central one, and four on 

 each side. Frontal lobe of the glabella short and wide : anterior 

 and middle lobes nearly equal, the dividing furrow marked only 

 at the side of the axis ; posterior lobe short and well defined 

 towards the axis; occipital furrow narrow; occipital ring wide 

 and strong. Eyes small, prominent, with about five lenses in the 

 vertical rows. 



The axis of the thorax is but little narrower than the lateral 

 lobes; the annulations somewhat flattened, and spreading towards 

 the extremities. The lateral lobes are flattened or a little concave 

 towards the axis, and, in their natural position, are bent abruptly 

 from the middle towards the exterior margins. The pygidium is 

 somewhat semicircular, emarginate, and a little concave behind : 

 the width, in a somewhat flattened specimen, is a little more than 



[ September, 



