ful predaceous sea serpent. The genus was founded by Cope in 1869; it has a wide distribution, and seven or eight species belong to it.
Tylosaurus proriger (Cope) is the third of Williston's type Kansas specimens perfected in restoration. It is considered the most specialized of the mosasaurs. The skeleton in hand is twenty-three feet in length, and shows a wholly cartilaginous carpus and tarsus, more elongated digits, and a greater number of phalanges than possessed by any other genus, the result of long aquatic habits. The hind paddles are the largest, and the fifth digit has undergone but little reduction, indicating characters of a very primitive rank. The vertebræ are more flexible than in other genera, but they are relatively smaller and not at all strong. The skull is more elongated anteriorly. In the same genus was a much larger species, T. dyspelor (Cope), which was one of the most formidable of the mosasaurs. Another perfected sea serpent of terrible powers was Mosasaurus horridus (Williston), which had a ram nose, and evidently battered its foes when he could get at them. Williston's perfect skull from Dakota enabled him to correct many errors in vogue. The new genus Brachysaurus, formed by Williston, contains one species defined by him—Overtoni, from Dakota. It had a stout, very broad head, stout jaws and teeth, and stout, broad paddles. In appearance it suggests a terrible fighter, unadapted to rapid pursuit or flight.
A number of remarkable skeletons of mosasaurs have been discovered of late, some of which are expected to develop new species and, perhaps, new genera. Few of the "finds" of explorers create such sensational interest in scientific circles as the unearthing of the gigantic saurians. Three new skeletons were lately taken by an exploring party of the American Museum of Natural History. Prof. W. T. Lee, of the University of Denver, was so fortunate not long since as to secure the first skeletons of mosasaurs ever taken in Colorado, and adds so much to the geographical distribution of the animals. One skeleton was taken at Flagler and another at Canyon City. The Flagler specimen was exposed for sixteen feet, the vertebral column containing ninety vertebrae. There were also taken portions of the head and paddles. Flagler is situated in the St. Pierre Cretaceous in all probability. The specimen, not yet named, has a massive jaw and teeth, the latter very compressed. The vertebral column is one of the most complete yet unearthed. The tail is particularly fine, and gives a good impression of depth and compression.
Williston thinks that the food of the sea-serpentlike saurians must have consisted of fishes of moderate size, with occasional victims of their own kind. He says: "While the flexibility and loose union
