612 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.49. 



The pelvic bones are all articulated and but little distorted by 

 crushing, though the ischia and postpubes have suffered the loss of 

 pieces since tlie specimen was collected. 



In the preservation of a portion of one of the sternal elements and 

 the greater number of the sternal ribs this specimen is unique, and 

 it contributes much to our better understanding of this portion of 

 dinosaurian anatomy. 



The importance of preserving articulated dinosaurian specimens 

 in their orighial position in the matrix can not be too highly estimated, 

 particularly where they give positive information, as in the present 

 specimen, relating to the proper articulation and angulation of the 

 feet and limbs. Unhke the mammals, in the dinosaurs the articular 

 surfaces are usually poorly defined, and afford little evidence con- 

 cerning the exact manner of articulation of bones found detached 

 and misplaced. So that any information conveyed by the finding 

 of an articulated specimen with bones in sequential position in the 

 rock is more to be relied upon than any number of expert opinions. 

 It was in deference to the above views that a decision was reached 

 regarding the present manner of exhibiting this specimen of Tliescelo- 

 saurus. 



I am also of the opinion that specimens so exhibited hold the 

 attention of the average museum visitor far longer and arouse a 

 keener interest in the genuineness of the specimen than does a skeleton 

 that has been freed from the rock and mounted in an upright, lif eHke 

 posture. 



To the layman the type of Thescelosaurus neglectus as now exhibited 

 is of interest as showing the skeleton in the same position as when 

 covered up millions of years ago, and to the vertebrate paleontol- 

 ogist it will long remain a standard for interpreting and coordinating 

 the scattered and isolated parts of others of its kind. 



CLASSIFICATION AND RELATIONSHIPS OP THESCELOSAURUS. 



The nonunion of the pubes in front of the sacrum, the slender post- 

 pubic processes extending parallel to the ischia, and the character- 

 istic birdlike hind feet show Thescelosaurus to be a true member of 

 the suborder Orthopoda, or Predentate dinosauria. 



In the first description * this genus was referred provisionally to 

 the family Camptosauridae, but after a more thorough study of the 

 type specimens I am now convinced that its family attributes are 

 with the Hypsilophontidae. The latest definition that I am able to 

 find of the family Hypsilophontidae is that of Zittel,^ which follows: 



Pramaxillaria zahnlos. Zilhne auf den Maxillaria in einer Reihe. Vordere Wirbel 

 platycol oder opishocol. Sacralwirbel verschmolzen. Femui- kiirzer als Tibia. 

 Hand mit 5 Fingern, Fuss mit 4 Zehen. 



» Gilmore, Charles W., Smiths. Misc. CoU., vol. 61, 1913, No. 5, p. 5. 

 * Grundziige der Palaontologie, 1911, pt, 2, p. 2S9. 



