Contributions to Paleontology. 



169 



GEOTJS TRIARTHRUS ? 

 SUBGENUS TRIARTHRELLA (n. s.). 

 TRIARTHRELLA AUR ORALIS ( n. s). 

 PLATE IV. FIG. 13. 



A small and obscure species occurs among the Dikelo- 

 cephali at Lagrange mountain, which has an elongate 

 semioval glabella, with the fixed cheeks wide and spread- 

 ing in the posterior limb, and very narrow in front. The 

 glabella shows an obscure indentation at its margin (not 

 so strongly as represented in the figure), and the general 

 expression is like Triarthrus. 



The species can hardly be characterized from the imperfect speci- 

 mens known, some four or five of which have been observed. 



Fig. 13. The glabella and fixed cheeks. The figure is twice the natural 

 size of the specimen. 



For notice of a species of Conocephalites belonging to the 

 first group of species indicated in this paper, see Explanations of 

 Plate ii. 



GENUS AGNOSTUS ( Brongniart). 

 AGNOSTUS JOSEPHA ( n. s.). 

 PLATE I. FIGS. 54 & 55. 



" Agnostus orion (?) Billings" : Shumard in Transactions Acad. St. Louis, 

 Vol. ii, p. 105. 



Not Battus [Agnostus~\ orion of Barrande, Notice preliminaire, p. 16, 1846 

 = Diplorrhina orion, Corda, 1847. 



Head semielliptieal, a little wider than long ; the sides 

 usually curving, sometimes straight for a part of their 

 length, margined by a flattened or concave narrow limb • 

 rather abruptly convex at the sides: the posterior mar- 

 gin, just within the angles, is produced on each side 

 into a short spine. 

 [Trans, v.] 22 



