112 THE CEEATOPSIA. 



Dana, J. D., Manual of Geology, 1895, p. 847. 



Lambe, L. M., Contr. Canadian Pal., vol. 3 (quarto > , pt. 2, 1902, p. 68. 



Marsh, O. C, Am. Jour. Sci., January, 1892, p. 83: December, 1S95, p. 497; Sixteenth Ann. Rept. U. S. Geol. Survey, 1896, 



pt. 1, pp. 217, 243. 

 Nicholson and Lydekker, Manual Pal., 1889, vol. 2, p. 1163. 

 Nopcsa, F. Baron, Foldtani Kozlony, Budapest, 1901, vol. 31, p. 270. 

 Osborn, H. F., Contr. Canadian Pal., vol. 3 (quarto), pt, 2, 1902, pp. 9, 20. 

 Woodward, A. S., Outlines Vert. Pal., p. 213. 

 Zittel, K. A. von, Text-book Pal., trans, by C. R. Eastman, vol. 2, p. 244. 



This genus, like the last-mentioned species of Agathaumas , was proposed but not described 

 in the footnote a portion of which is quoted above. " The genus is described as follows: 



Char. gen. — A species considerably larger than the last (Cionodon arctatus), represented by vertebra? and numerous 

 fragments of limb bones. The most characteristic of the former are two probably from the posterior dorsal region, which 

 are somewhat distorted by pressure. The more anterior is shorter than the other and exhibits both anterior faces slightly 

 concave, the one more so than the other. They are higher than wide and the border is scalloped above for the capitular 

 articulation for the rib. There are numerous nutrient foramina and some ligamentous pits on the articular surfaces. The 

 inferior face is rounded. In the larger vertebra both faces are more strongly concave, and at each end of the lower side there 

 is an obtuse hypopophysial tuberosity. The sides of the centra of both vertebra? are concave. The neural canals are 

 relatively small and the neurapophyses coossified. A third vertebra without arches is similar in specific gravity, though 

 without the white surface layer of the others. It is appropriate in size and form to this species, and is peculiar in its flat 

 form, resembling the anterior dorsals of the Hadrosaurus. In this respect it is related to the shorter vertebra of the two 

 above described as the latter is to the longer. The surface of the posterior articular surface is damaged; it was not concave, 

 and is now slightly convex; the anterior is preserved and is concave. 



Only one species of Polyonax has been described, namely, P. mortuarius Cope. This will 

 now be noticed. 



Polyonax mortuarius Cope. 1874. 



Type (No. 3950, American Museum of Natural Historj') consists of fragments of horn cores, vertebra?, etc. 



Original description in Bull. U. S. Geol. and Geog. Surv. Terr., vol. 1, No. 1, 1st ser., 1874, p. 10, footnote. 

 Cope, E. D., Ann. Rept. U. S. Geol. and Geog. Surv. Terr, for 1873 (pub. 1875), pp. 448, 451-452; Bull. U. S. Geol. and Geog. 



Surv. Terr., vol. 1 , No. 2, 1st ser., 1S74, pp. 7, 21, 25; Rept. U. S. Geol. Surv. Terr., vol. 2, 1875, pp. 26, 59, 64-65; Am. 



Naturalist, vol. 23, 1889, p. 715, 716. 

 Nopcsa, F. Baron, Foldtani Kozlony, Budapest, 1901, vol. 21, p. 270. 

 Osborn, H. F., Contr. Canadian Pal., vol. 3 (quarto), pt. 2, 1902, p. 14. 



This species, like the genus to which it was referred, was first named without being 

 described in the footnote mentioned and in part quoted above in connection with our remarks 

 on Agathaumas milo. In Bulletin No. 2, United States Geological and Geographical Survey of 

 the Territories, page 25, after the diagnosis of the genus Polyonax just quoted, Cope defines 

 the present species as follows: 



The articular faces are deeper than wide in the vertebra?; the sides are smooth; the lower faces narrow and probably 

 keeled. 



, Measurements. Mm 



Anterior dorsal , length of centrum 0. 048 



Anterior elevation of neural canal 094 



Anterior width : . 094 



Median dorsal, length of centrum _ 057 



Median elevation to neural canal ' 117 



Median width 083 



Posterior dorsal , length of centrum 092 



Posterior dorsal, elevation 104 



Posterior dorsal, width 083 



Posterior dorsal, diameter of neural canal - . 015 



The measurement of the neural canal is made near the base of the neurapophyses and is probably a little affected by 

 pressure. 



The limb bones embrace portions of tibia, fibula, and some others not yet determined. The portion of tibia is from 

 the base of the cnemial crest, so that one extremity is trilobate, the other transverse oval. The former outline indicates 

 iwo posterior tuberosities. The bone is solid and the superficial layer, for 3 mm. or less, is so dense and glistening as to 



a Bull. No. 2, U. S. Geol. and Geog. Surv. Terr., 1st ser., 1874, pp. 24 and 25. 



