PTERANODON. _Pteranodon_ Marsh, Amer. Journ. Sci. xi, p. 508, June 1876; and xii, p. 479, Dec. 1876; xxiii, p. 253, April, 1882; xxvii, p. 423, May, 1881; Williston, Amer. Naturalist, xxv, p. 1174, Dec. 1891 =Pteranodon occidentalis.= _Pterodactylus Oweni_ Marsh, Amer. Journ. Sci. i, p. 472, June 1871, Sep. p. 16 (nom. preoc). _Pterodactylus occidentalis_ Marsh, Amer. Journ. Sci. iii, p. 242, April 1872, Sep. p. 1; Cope, Cretac. Vert. p. 68, pl. vii, ff. 5, 6. _Ornithocheirus harpyia_ Cope, Proc. Amer. Phil. Soc. 1872, p. 471 (Cope). This species was originally based upon the distal end of two wing-metacarpals, and teeth. In the following year, a fuller description was given of additional remains referred to the same species and renamed _P. occidentalis_. =Pteranodon ingens.= _Pterodactylus ingens_ Marsh, Amer. Journ Sci. iii, p. 246, April 1872, Sep. p. 6. _Pteranodon ingens_ Marsh, Amer. Journ. Sci. xi, p. 508, June 1876. This species is based upon various bones of the wing-finger of several individuals, and three teeth. =Pteranodon umbrosus.= _Ornithocheirus umbrosus_ Cope, Proc. Amer. Phil. Soc. 1872, p. 471. _Pterodactylus umbrosus_ Cope, Cret. Vert. p. 65, pl. vii, ff. 1-4. Marsh (Amer. Journ. Sci. xii, p. 480, Dec. 1876) says this name is a synonym of _P. ingens_, published two days earlier. As this synonymy is not certain, and as Cope’s species has been figured, I am not ready to accept his views. =Pteranodon velox.= _Pterodactylus velox_ Marsh, Amer. Journ. Sci. iii, p. 247, April 1872, Sep. p. 8. Based upon the distal end of the right metacarpal of the wing-finger, and the proximal extremity of the adjoining first phalanx, two uncharacteristic parts of the skeleton, Marsh to the contrary notwithstanding. It is doubtful whether the direct comparison of the types will suffice to determine the species with certainty. “Both of the bones are somewhat distorted by pressure.” =Pteranodon longiceps.= _Pteranodon longiceps_ Marsh, Amer. Journ. Sci. xi, p. 508, June 1875; xxvii, p. 424, pl. xv, May 1884. Based upon a somewhat defective skull, without other bones. There is no evidence whatever that the species is distinct from the preceding. =Pteranodon comptus.= _Pteranodon comptus_ Marsh, Amer. Journ. Sci. xi, p. 509, June 1876. Based upon wing-bones of three individuals. The description is meagre. =Pteranodon nanus.= _Pteranodon nanus_ Marsh, Amer. Journ. Sci. xxi, p. 343, April 1881. Based upon various remains of one individual; the humerus, alone, is recognizably described. NYCTODACTYLUS. _Nyctosaurus_ Marsh, Amer. Journ. Sci. xii, p. 480, Dec. 1876. (nomen preoc.[1]). _Nyctodactylus_ Marsh, Amer. Journ. Sci. xxi, p. 343, April 1881: ibid. xxvii, p. 423, May 1884.