THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE V. VOL. 11. 



No. VL — JUNE, 1905. 



(D:RX(3rXl<rA.lL, ^^I^TICXjES. 



I. — Notes on British Dinosaurs. Part II : Polacanthus. 



By Dr. Francis Baron Nopcsa. 



(PLATE XII.) 



NEXT to HypsilopJiodon ^ it was Polacanthus whicli attracted my 

 attention. A careful study soon showed that, after the death 

 of the animal, the remains of some Crocodilian had accidentally 

 become commingled with this Dinosaur. Besides this, some pieces,, 

 namely, the back part of a skull and a cervical, showed remarkably 

 Iguanodon-VikQ characters, and the same is also true of the pubic 

 bone described by Seeley in 1892 as belonging to Polacanthus. 



As I intend pointing out further on, and as has also already been 

 done by Seeley, Polacanthus was constructed essentially after the 

 Struthiosaurus plan, and this is the reason why this Iguanodon-like 

 basi-occipital has to be removed from the Polacanthus remains. 



For the removal of the pubic bone from the genus Polacanthus^ 

 similar arguments can be brought forward. 



(1) The ischium and pubis are two closely correlated bones, and 

 as the ischium of Polacanthus is totally different from that of 

 Iguanodon the same was to be expected as to the pubis. 



(2) Both ischium and pubis are correlated with locomotion, and 

 as Iguanodon was a bipedal and Polacanthus, on the contrary, 

 a quadrapedal animal, we again cannot expect Polacanthus to have 

 an Iguanodon-li^e pubis. 



Since the so-called Polacanthus pubis differs from Iguanodon 

 only by being somewhat shorter,- and agrees very well with 

 the Iguanodon-like basis cranii and cervical vertebrae, I think it 

 may quite well belong to an Iguanodon - like animal, and not to 

 Polacanthus. 



1 ¥oi mjpsilophodon, see Geol. Mag., May, 1905, pp. 203-208. 



2 Even this may be due to fracture. 



decade t. — VOL. n. — no. yi. 16 



