SYSTEMATIC SYNOPSIS OF FOSSIL BIEDS. 827 



IcMhyornis and ArcTuBoptert/x, shows greater diversity from one aiK.itlier than that existiiii; 

 among all known birds of hiter geologic and of the present epoeh. 



The first remains of tliis now famous species were found by Prof. Jfarsh in November, 

 1870, in the yellow chalk; of the Pteranodon beds, near the Smciky Hill river in Kansas. The 

 type specimen was found in July, 1871, on the south bank of the same river, about twenty 

 miles east of Fort Wallace, imbedded in gray calcareous shale. Many other remains have 

 also been collected, representing in all some forty different individuals, all from the same 

 geologic horizon in Western Kansas, and most of them near the locality of the original ones. 

 They are all preserved in the Museum cjf Yale College. 



31. HESPERORNIS CRASSIPES. 



Lestornis erassipes, Marsh, Am. Joum. Sci., xi, June, 187R, p. 509. 



Hesperornis erassipes, Marsh, Odont., 1880, p. 190, figg. 40 a-d. pll. vii, xvii. 



Based upon a nearly complete skeleton from the yellow chalk of Western Kansas, indicat- 

 ing a bird considerably larger than H. regalis, and one that may prove to be geuerically 

 distinct. Deposited in the Yale Museum. 



32. HESPERORNIS GRACILIS. 



Hesperornis graeilis, Marsh, Am. Journ. Sci., xi, June, 1876, p. 510. — Id., Odont., 1880, 

 pp. 99, 197. 



A third species, from the same horizon and locality, represented by two specimens, one of 

 them a nearly complete skeleton. Deposited in the Yale Museum. 



33. ICHTHYORNIS DISPAR. 



Ichthyornis dispar, Marsh, Am. Journ. Sci., iv, Oct., 1873, p. 314. — Id., Hid., v, Feb., 

 1873, p. 161. — Id., ibid.. Mar., 1873, p. 230. — Coues, Key, 18/2, p. 350. — Owen, Journ. 

 Geol. Soc. Loud., xxxix, 1873, p. 520. — WooDW., Pop. Sci. Rev., Oct., 1875, p. 348. — Marsh, 

 Am. Nat., ix, Dec, 1875, p. 625. — Id., Geoh Mag., iii, 1876, p. 49. — Huxl., Pop. Sci. 

 Monthly, X, 1876, pp. 215-218. —Marsh, Journ. de Zool., iv, 1875, p. 494, pi. xv ; vi, 1877, 

 p. 385. — Id., Odont., 1880, pp. 119-183, 197, pU. xxi-xxvi. 



This remarkable bird, forming a type of the whole group Odontotormm (p. 237) of Odont- 

 ornithes, with general characters of the skeleton like those of ordinary birds, yet with socketed 

 teeth and biconcave vertebrae, was discovered in 1872 near the Solomon river in Northwestern 

 Kansas, in the Pteranodon beds of the middle Cretaceous. It vras about as large as a pigeon. 

 The remains of about nine individuals, all from the same region, are preserved in the Museum 

 at Yale College. 

 34.* ICHTHYORNIS AGILIS. 



Graculavus agilis, Marsh, Am. Journ. Sci., v. Mar., 1873, p. 230. 



Ichthyornis agilis, Marsh, Odont., 1880, p. 197. 



Prom the same horizon in Western Kansas, on Butte Creek, a tributary of the Smoky 

 Hill river, where discovered in October, 1872. The remains are preserved in the Yale College 

 Museum. 



35. ICHTHYORNIS ANCEPS. 



Oraculavus anceps. Marsh, Am. Journ. Sci., iii. May, 1872, p. 364. — Coues, Key, 

 1872, p. 350. —Marsh, Am. Journ. Sci., v. Mar., 1873, p. 229. — Id., Odont, 18S0, pp. 

 124, 198. 



Resembling I. dispar, but with slenderer jaws and more teeth. The right lower jaw of 

 the type specimen of 1. dispar shows twenty-one distinct sockets. Discovered in November, 

 1870, in the gray shale of the middle Cretaceous, on the north fork of the Smoky Hill river in 

 western Kansas, where other specimens have since been found. All are preserved at Yale. 



36. ICHTHYORNIS LENTUS. 



Graculavus lentus, Marsh, Am. Journ. Sci., xiv, Sept., 1877, p. 253. 

 Ichthyornis lentus. Marsh, Odont., 1880, p. 198. 



