THE DINOSAURS 107 



ran series of large, but thin, and sharp-edged 

 plates standing on edge, so that their backs 

 looked like the bottom of a boat provided with 

 a number of little centreboards. Just how 

 these plates were arranged is not decided be- 

 yond a peradventure, but while originally fig- 

 ured as having them in a single series down 

 the back it seems much more probable that 

 they formed parallel rows. 



The largest of these plates were two feet in 

 height and length, and not more than an inch 

 thick, except at the base, where they were en- 

 larged and roughened to give a firm hold to 

 the thick skin in which they were imbedded. 

 Be it remembered, too, that these plates and 

 spines were doubtless covered with horn, so 

 that they were even longer in life than as we 

 now see them. The tail spines varied in length, 

 according to the species, from eight or nine 

 inches to nearly three feet, and some of them 

 have a diameter of six inches at the base. 

 They were swung by a tail eight to ten feet 

 long, and as a visitor was heard to remark, one 

 wouldn't like to be about such an animal in 

 fly time. 



