152 SIXTEENTH REPORT ON THE CABINET OF NAT. HISTORY. 



broad, and the border narrow. The frontal limb has a wide and 

 deep groove in front of the glabella, with an abruptly raised 

 narrow anterior border, the whole being curved suddenly down- 

 wards at the anterior lateral angles. 



This species is conspicuously distinct from any of the others hy its very 

 gibbous glabella, which is nearly equal in length and width. The posterior 

 and medial glabella-furrows are well marked, but there is no distinct in- 

 dication of the anterior one. 



Specimens containing this fossil were derived from a loose mass of sand- 

 stone at Trempaleau, apparently from the beds near the locality, since it 

 was little worn. From the character of the-rock, its position is probably 

 between the extreme lower and middle fossiliferous beds. 



The three preceding species have the form of glabella which is 

 characteristic of Conocephalites, and the facial suture cuts the 

 frontal contour at a point distant irom the apex. In the last one, 

 however, the direction of the suture-line in its posterior course is 

 different from the others, and there is a distinct groove defining 

 the palpebral lobe ; a feature not observed in the other two. 



In the following species, the glabella is conical, and more or 

 less distinctly marked by oblique furrows. The suture-line par- 

 tially cuts the anterior border at a point distant from the apex, 

 but a narrow portion of the cheek-border extends along the frontal 

 limb nearly or quite to the apex. This course of the suture-line 

 produces a sloping or curved outline from the apex to the lateral 

 margin of the frontal limb. The fixed cheeks are very narrow, and 

 prominent towards the eye; but in none of them are there well- 

 marked ocular ridges, and the palpebral lobe is not observed to 

 be distinctly limited by a groove, except in C. anatinus. In the 

 latter character there is no departure from typical Conocepha- 

 lites; but in tlie course of. the suture-line in front, there is a 

 departure from the recognized species of that genus. 



The species thus grouped are the C. perseus^ C. sfiumardi, C. 

 nasutus^ C. oweni, C. eryo?i, C. anatinus and C patersoni. 



Among the remains of some of these species we find the " dou- 

 blure^'' or lower border of the frontal limb, separated as a single 

 piece ; presenting a feature somewhat similar to the corresponding 

 part of Paradoxides, except that its continuity on the posterior 

 margin is not broken by the attachment of the hypostoma. This 

 portion of the front, however, has a distinct, central, vertical 

 suture, as in Asaphus (See fig. 38 a, Plate vii ). 



Should the species possessing these features be found to require separation 

 from Conocephalites, I would propose the name Conaspis. 



