TRICF.RATOPS 



115 



Level 

 High 



19 



20 



21 



22 



23 



24 



25 



26 



27 



28 



29 \ 



30 | 

 31 

 32 



Low 



Museum 



V.P.M. 



T.S.N.M. 

 U.S.N.M. 

 U.S.N.M. 

 U.S.N.M. 

 U.S.N.M. 

 U.S.N.M. 

 U.S.N.M. 

 U.S.N.M. 

 U.S.N.M. 



U.S.N.M. 



Y.P.M. 



U.S.N.M. 



Catalogue 

 number 



1822 

 7239 

 1208 

 6679 

 5741 

 1205 

 4708 

 4286 

 2124 

 5738 



2416 



1820 

 4720 



Type 

 Holotype 



Holotypc 

 Holotype 



Genus 



frieeratops 

 frieeratops 

 fr'neratops 

 frieeratops 

 Trneratops 

 Trneratops 

 Frieeratops 

 Trneratops 

 1 rieeratops 

 frieeratops 



and species 

 prorsus 

 sp. indet. 

 sulcatus 

 sp. indet. 

 elatus 

 prorsus ? 

 elatus 

 sulcata* 

 sp. indet. 

 sp. indet. 



'frieeratops serratus 



'frieeratops horridus 

 Triceratops obtusus 



Thirteen species of Triceratops have been described, all but four being based upon adequate 

 material, in every instance a more or less complete skull, together with a varying number of skeletal 

 parts. The skeletal material does not at present offer any characters, other than that of size (see 

 T. ma.xhnus), which may be used for specific determination, and it is to be doubted whether entire 

 skeletons in each instance would show material variation other than size, with some differences of 

 proportions, and possibly the relative height of the spinous processes of the dorsal vertebrae, corre- 

 lated with the development of the crest of the skull and its degree of freedom from the underlying 

 flesh, as shown by the extent of the vascular impressions on its under side. 



We have determined certain common factors in all of the type skulls which are in any degree 

 complete, but find difficulty in deciding as to their relative specific value, for a grouping of specimens 

 according to the character of the nasal horn may give a different idea of relationship from that 

 derived from the character of the brow horns, and so on. Nevertheless, it has been possible to 

 recognize certain assemblages of species, but the reduction of the total number has not been satis- 

 factory, even though the practice of giving a distinct specific name to every approximately complete 

 skull, which was actually done, seems, a priori unreasonable. 



Of the new material which has come to light since the Ceratopsia Monograph was published in 

 1907, all, with the possible exception of the skull of the mounted skeleton in the American Museum, 

 and the huge vertebrae described by Brown/' may be correlated with forms already described. 

 There are a few skulls of the older Marsh Collection at the Yale Peabody Museum, which, because 

 of lack of complete preparation or other inaccessibility, have not been studied in full detail, but the 

 inference is that all would be found referable to already known species. 



The species, in order of their publication, but grouped also according to adequacy of the type 

 materia], are as follows: 



Triceratops 

 Triceratops 

 Triceratops 

 Triceratops 

 Triceratops 

 Triceratops 

 Triceratops 

 Triceratops 

 Triceratops 



Adequate 



horridus Marsh, 1889 



flabellatus Marsh, 1889 



prorsus Marsh, 1890 



serratus Marsh, 1890 



elatus Marsh, 1891 



calicornis Marsh, 1898 



obtusus Marsh, 1898 



brevicornus Hatcher, 1905 



(Diceratops) hatcheri Lull, 1905 



Inadequate 

 Triceratops alticornis Marsh, 1887 

 Triceratops galeus Marsh, 1889 

 frieeratops sulcatus Marsh, 1890 

 Triceratops maximus Brown, 1933 



59 T. maximus, Brown, B, 1933, A. 



