Antero-posterior expansion 40 millim. Length of symphysis 14 Expanse of the united bones, as flattened 90 Width of ischial process 11 NYCTODACTYLUS. The type species of this genus was described as follows by its author (loc. cit. supra): “One of the smallest American species yet found is represented in the Yale Museum by several bones of the wing, a number of vertebrae and the nearly complete pelvis. The wing-bones preserved are elongated and very slender. The pelvis is unusually small, and there are five vertebrae in the sacrum. The last of the series indicates that the tail was short. The following are the principal measurements of this specimen: Length of ulna 187 millim. Length of metacarpal of wing-finger 300 Antero-posterior diameter of outer condyle at distal end 15 Transverse diameter of shaft, above condyles 13 Length of first phalanx of wing-finger 347 Extent of five vertebrae of sacrum 57 This species, which may be called _Pteranodon gracilis_, was about two-thirds the size of _P. velox_ Marsh. It probably measured about ten feet between the tips of the expanded wings.” In the December number of the same volume of the American Journal of Science, he described the genus as follows: “A second genus of American Pterodactyls is represented in the Yale Museum by several well preserved specimens. This genus is nearly related to _Pteranodon_, but may be readily distinguished from it by the scapular arch, in which the coracoid is not co-ossified with the scapula. The latter bone, moreover, has no articulation at its distal end, which is comparatively thin and expanded. The type of this species is _Pteranodon gracilis_ Marsh, which may now be called _Nyctosaurus gracilis_. It was a Pterodactyl of medium size, measuring about eight to ten feet between the tips of the expanded wings.”