168 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



mens, a distinct ocular ridge extending from the palpebral lobe 

 in the direction of the front of the glabella : posterior limb 

 unknown. Frontal limb much expanded, with a narrow flattened 

 space beyond the groove, and, rising abruptly, it spreads in a 

 broad flattened border which is apparently not thickened upon 

 its margin. 



A movable cheek in the same association is elongate triangular, 

 with a large ocular sinus : the posterior angle is produced into 

 a long curving spine ; the body of the cheek is convex, with a 

 wide flattened border. 



The measurements of the head are as follows : Length of gla- 

 bella anterior to the occipital furrow, 0'36 of an inch; width at 

 base, 0-30 ; width at the anterior end, 0*24 ; entire length of 

 head, 0*61 ; frontal limb, 0'18 of an inch. 



A pygidium, fig. 21, found in the specimens from Marine mills, which 

 appears to be too large for any individual of G. oweni, I suppose may belong 

 to this species. It is more than twice as wide as long ; the axis abruptly 

 elevated, and marked by six annulations, including the anterior one ; the 

 lateral lobes are nearly flat, and marked by three divided ribs besides the 

 anterior one, all terminating in a flattened border. A single specimen, 

 larger than this one, has been seen. 



PLATE VII. 



Fig. 36. The glabella and part of the fixed cheeks, showing ocular ridges. ( The spe- 

 cimen is of medium size, from Marine mills.) 



Fig. 37. A part of a larger head, with the glabellar furrows more strongly marked. 



Fig. 38. A cheek associated with fig. 37, and probably of the same species. The figure 



shows the course of the facial suture and the extension of the border on the 



lower side, which reaches beneath the frontal limb. 



PLATE VIII. 



Fig. 18. A glabella and frontal limb, in which the space between the front of the 

 glabella and the elevated border is much narrower than in the other speci- 

 mens. 



Fia. 21. A pygidium which occurs in the same association. 



This species is comparatively rare : a few individuals occur in some speci- 

 mens from the Marine mills on the St. Croix river, with large numbers of 

 Conocephalites oweni. It is very distinct from any other, in the depressed 

 flattened area just forward of the glabella, and the abrupt elevation and 

 flattened anterior border. There is considerable diversity of expression 

 given to this species, from the greater or less extent of the depressed flat- 

 tened portion of the limb in front of the glabella, and also from the im- 

 perfection of the anterior border of the limb, which sometimes leaves it 

 little wider than the posterior flattened space. 



I have collected the same species on the west side of the St. Croix river, 

 /^ about two miles below the Falls. 



