7 24 THE POPULAR SCIENCE MONTHLY. 



On September 26, 1872, Silliman's American Journal of Science 

 announced the disinterment of another skeleton from the chalk of 

 Kansas, " one of the most interesting of recent discoveries in paleon- 

 tology." The remains included, among other bones, a number of bi- 

 concave vertebrae, that is, having the bodies, or solid central piece of 

 the spinal segments, cup-shaped at both ends, a configuration which 

 obtains, as every one has observed, in the divisions of the backbone of 

 the common cod. This characteristic of the spine is frequent enough 

 among reptiles ; but it never occurs among birds met with nowadays. 

 If among them there be any tendency that way, as there is in a few 

 birds, the concavity is invariably found in the posterior end, the rarest 

 form of vertebras among reptiles. " The neck, back, and tail vertebra? 

 preserved, all show this character, the ends of their bodies (centra) 

 resembling those in the plesiosaurs ; " notwithstanding the strongly 

 non-Avian description of the spine, all the other bones the promi- 

 nently keeled breastbone, the collar-bone united to form a " merry- 

 thought," as well as the leg- and long wing-bones exhibit those marks 

 which we have found to be most typical of the bird tribe. The wings 

 were large in proportion to the posterior extremities ; and the lower 

 end of the leg-bones is incurved as in swimming-birds. Prof. Marsh, 

 therefore, judging from their relative proportion, concludes that the 

 bones belonged to a bird about the size of a pigeon, in many respects 

 resembling the aquatic birds. He has christened it Ichthyornis dis- 

 par. 



In October of the same year this indefatigable geologist once more 

 announced through the pages of Silliman a new " find " from his 

 favorite and fruitful mine in Upper Kansas. This time it was " a new 

 reptile from the cretaceous ... a very small saurian, which differs widely 

 from any hitherto discovered." The only remains found on this occa- 

 sion were two lower jaws, nearly perfect, and with many of the teeth 

 in good preservation. The jaws resemble in general form those of an 

 extinct family of marine reptiles whose remains were first found in the 

 chalk formation near Maestricht ; but apart from their very diminutive 

 size they present several features which no species of that group has 

 been observed to possess. Noticeably, the teeth are implanted in dis- 

 tinct sockets, and are directed obliquely backward. There are appar- 

 ently twenty in each jaw, all compressed, with very acute summits. 

 Then there is no distinct groove on the inner surface of the jaws as in 

 all known Mososauroids as the family of Maestricht reptiles is named. 

 " Clearly," says Prof. Marsh, " the specimen indicates a new genus." 



A more careful removal of the surrounding shale brought to light a 

 fact that enormously enhanced the importance and value of this " most 

 interesting of recent discoveries in paleontology." The jaws, which 

 had been accredited to " a new genus " of reptiles, belonged most un- 

 doubtedly, from the position in which they were found with reference 

 to the other bones, to the Ichthyornis dispar, which owned the spine 



