248 Dr. Francis Baron JVojjcsa — British Dinosaurs. 



strongly displaced, and it is only in the caudal region that we find 

 them comparatively in order. 



On the middle part of the tail one can clearly distinguish 

 three roof-like plates, one placed on each diapophysis of the 

 centrum and one on the neurapophysis of the arch. Further 

 back one can only observe two roof-like, somewhat asymmetrical 

 plates placed latei'ally of the neurapophysis and above the 

 diapophysis, thus allowing space for the musculns lateralis caudse. 

 A thicker plate is visible in one place laterally of the chevron 

 bone. In Diracodon, Stegosaurus, and Dacenlurus (Omosaiirus) 

 we know that the end of the tail was protected by a double row 

 of spines, while the anterior caudals and all the other vertebrse 

 supported one median row of high plates, which in consequence 

 of their abrupt posterior margin were pointed somewhat backwards 

 and formed an acute dorsal ridge. 



Fig. 6. — One pair of dermal caudal plates of Polacanthtis (preserved united in 

 matrix), side view. 



The probably complex armour of the Ceratopsidse is altogether 

 unknown, and the same is true for AcantJiopholis and Strntliiosaurtis. 

 Besides Scelidosaurus, ITylcBosmirits is the only European armoured 

 Orthopodous Dinosaur in which the armour is still partly m situ, and 

 though somewhat disturbed, one can notice that this Dinosaur 

 possessed at least two rows of lofty spines which, beginning directly 

 behind the head, inci'ease rapidly in height and attain their maximum 

 development and sharpness in the scapular region. This reminds 

 one to a certain degree of the armour of the Iguana tuberculata. 

 The lumbar region of Hylceosaurus is nearly unknown, and in the 

 tail only button-like ossifications seem present. 



Turning back to Folacautlins, the piece figured by Ilulke and 

 fragments which I succeeded in uniting prove that some of the roof- 

 like plates and button-like pieces belong to the armour of the tail. 

 By placing all the roof-like plates in one row beside the caudal 

 vertebra it soon, however, became evident that this was not their 

 natural position, for the row they formed in this way is just about 

 twice as long as the entire series of caudal vertebrae. 



This circumstance drew my attention to numerous facts not yet 



