138 NEW YORK STATE MUSEUM 



angular area. The prevailing aspect of the cranidium and glabellar lobes 

 is that of narrowness and length, particularly in the distance between the 

 nuchal furrow and the frontal lobe. The nuchal furrow is broad and low 

 and the occipital ring broad, flat and arched. 



Spines. While the general surface is tubercled and some of the tuber- 

 cles become developed into short spines the major spines are as follows : 

 three pairs, one in front of another on the crest of the glabella ; these are 

 of great size and strength and deeply curved backward. They seem to be 

 all of about the same length. In some of our specimens the posterior pair 

 curves backward in a long arch to and beyond the posterior margin of the 

 head, but in a younger specimen they are shorter. The middle and anterior 

 pairs are quite as long. In section these great frontal spines or hooks are 

 not circular but somewhat flattened on the opposing faces, rounder on 

 the outer surface and narrow fore and aft. In our first preparation of these 

 specimens we found only two pairs of these spines but material subsequently 

 acquired indicates that there were three. 



On each lateral lobe where widest, and just above the dorsal furrows, 

 is a spine of less hight than the foregoing and apparently erect and these 

 are flanked in front by a much shorter pair. These five pairs seem to be 

 all there are on the glabella except for the spinous tubercles in the occipital 

 area. 



The occipital ring bears at its edge on the axis a series of long curved 

 flat or vertically compressed spines, one at the middle and one diverging 

 from the axial spine, at each side. These are neither as long nor as large as 

 those of the frontal lobe but they must have reached back over several of 

 the thoracic segments. The occipital ring is deeply contracted at the dorsal 

 furrows and where it expands again beneath the cheeks it extends, on each 

 side, out into a flat but straight and slender spine larger than the others. 

 This makes five spines on the neck ring, fifteen in all on the cranidium, 

 seven pairs and one axial. It would be natural to expect others on the 

 palpebral lobe but these seem to be wanting. 



The other parts of the species are represented by portions of free 

 cheeks which indicate that these ran out into short, thick and narrow genal 

 extensions with a row of rather small spines along the occipital margin, 

 while just outside of the eye near the margin there was a very large, long 

 and recurved hook like those of the frontal lobe. There is still some uncer- 

 tainty as to the exact details of these parts, due in large measure to the 

 difficulty of extracting them from the rock. 



The features here present constitute the most extraordinary develop- 

 ment of spines yet observed amongst the trilobites. Yet upon consideration 

 of the generic relations of the species and its affiliation with previously 

 known forms we may observe that this extreme spinosity is the manifesta- 

 tion of epidermal excrescence which has long been recognized as the accom- 



