98 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 55. 



the pattern of the scales may have varied considerably in the differ- 

 ent genera, as they are known to do in the various Trachodont genera. 



Since this model was prepared in 1915, a second Ceratopsian speci- 

 men (type of Monoclonius cutleri Brown) having impressions of the 

 skin preserved has been discovered. According to Brown ^ the 

 polygonal scales extended down over the belly, instead of the small 

 rounded scales here represented as covering those parts in the model, 

 but, of course, we can not be certain that the same arrangement of 

 the scales prevailed in the genus Triceratops. 



One other noticable departure from earlier restorations is in free- 

 ing the femoral part of the hind limb from the flank, thus adopting 

 a reptilian form of limb, rather than the mammalian form pre- 

 viously used. 



Future discoveries may show many features of the present restora- 

 tion to be incorrect, but at the least it graphically portrays some of 

 the discoveries made during the past 10 years, in our knowledge of 

 the probable life appearance of these huge-headed reptiles now so 

 long extinct. 



NOTES ON THE OSTEOLOGY OF TRICERATOPS. 



The entire collection of vertebrate fossils, in the United States 

 National Museum, from the Lance formation of Wyoming has now 

 been prepared for study and exhibition. This collection, made by the 

 late J. B. Hatcher and his associates during the years 1889 to 1891, 

 formed a part of what is known as the "Marsh collection" trans- 

 ferred to the Museum by the United States Geological Survey. 



In the course of this work, specimens were found which contribute 

 to a better understanding of the osteological structure of certain 

 members of the Ceratopsia, and especially important was the uncov- 

 ering of additional bones pertaining to the type-specimens on which 

 Triceratops ohtusus Marsh and Triceratops calicornis Marsh were 

 founded. 



Notes relating to the more important of these specimens are given 

 in the following pages. 



THE TYPE-SPECIMEN OP TRICERATOPS OBTUSUS MARSH. 



The tj^pe of this species as enumerated by Hatcher ^ in 1907, con- 

 sisted of " a pair of mandibular dentaries and the anterior portion 

 of the nasals, a left maxillary, a squamosal parts of a pterygoid, and 

 a vertebra." The finding of nearly the entire remaining parts 

 of the skull (see pi. 4) is a welcome addition to the above material, 



1 Bull. Amer. Mus. Nat. Hist., vol. 37, art. X, 1917, p. 299, pi. 18. 



* The Ceratopsia, Monograph 49, U. S. Geological Survey, 1907, p. 140. 



