THE CERATOPSIA. 



65 



THE EXOSKELETCXTST. 



Various spines and dermal plates have been found, more especially in the Laramie, associated 

 with remains of the Ceratopsia and other dinosaurs. None of these have yet been found in 

 such association as would dem- 

 onstrate conclusively that they 

 pertained to any member of the 

 Ceratopsia, and nothing is posi- 

 tively known as to the positions 

 occupied by any of these ossifica- 

 tions in the anatomy of the ani- 

 mal. A few of these are shown 

 here in fig. 74, but considering 

 the limited knowledge we at 

 present possess concerning them 

 it seems scarcely worth while 

 to speculate as to the positions 

 they occupied. The asymmetri- 

 cal spines, one of which is shown 

 in fig. 74, 1, 2, 3, may have been 

 arranged in pairs at the base of 

 the tail, and it is not impossible 

 that the plates shown in 4-10 

 and others similar to them may 

 have been so embedded in the 

 skin as to have formed a cuirass 

 or armor about the throat and 

 over certain regions of the back. 

 The curious group of little ossi- 

 cles coossified about a common 

 base, shown in 11 and 12, were 

 found associated with a consid- 

 erable portion of a skeleton of a 

 member of the Trachodontida?, 

 though not in such manner as to 

 demonstrate conclusively that it 

 pertained to that skeleton. No 

 Ceratopsia remains were found 

 with it, however, and it would seem probable that it pertained to the associated skeleton were it 

 not for the fact that no such ossifications were found associated with the two nearly complete 

 skeletons of that trachodont collected by the writer in the same deposits. 

 mon xlix — 07 5 



12 



'fiih 



Fig. 74. — 1-3, Side, front, and top views of dermal spine; 4-7, top. bottom, side, and end 

 views of dermal plate; 8-10, top, side, and bottom views of dermal plate. All the 

 above figures are one-eighth, natural size. 11-12, Side and front views of dermal 

 ossifications found with portion of skeleton of JDiclonius. One-half natural size. 

 After Marsh. 



