(I Ptirhtipntl front tin (%nithriihjf l^jiptr ( ! rei nstiiiil. ,'U)J) 



rudimL'iital <li,:;it wen- tally jxrcnvn, it would J)im1j;i1i1v show 

 the features " whieh elwiraeterize the cUnv-pliahinx which lias 

 been mistaken for tlie horn of Iijuanoffon,''^ That iiorn lias 

 been harpi'd unon .so steadily, that I will venture to wind it 

 once more. First, then, it is nianit'i'st that the detcriuination 

 quoted is as ])ure a dn-ani as a niidsunnner night could invent. 

 Hut in 1S,")4 (Wealden Dinosauria, ])art 2) the illustrious au- 

 thor devoted many jiai^^es to a consideration upon this horn ; 

 and there, too, the bone wliicli Dr. Mantell so confidently ex- 

 alted is deprraded to beinti: the support for an Tuuanodon's toe- 

 nail, seemingly because Dr. Mantell had named it a horn. I do 

 not wish to defend Dr. Mantell, though 1 think that his scien- 

 tific instinct led to a conclusion Avhieh was ])hiloso])hically 

 good; nor do I wish to underrate the spirit of Prof. Owens 

 protest that lyuanodon can by no means be inferred to have 

 had a horn because such a structure is found in Iguana. 

 Even if wrong in this particular case, it w\as important for the 

 progress of science that uniformitarianism should not creep 

 uno])poscd into comparative anatomy. But in the elucidation 

 of the truth it is desirable not to neglect facts ; and from the 

 time when Prof. Owen observed that '' the mutilated basal 

 surface in no wise militates against the supjX)sition of the co- 

 nical bone having been the terminal unsyrametrical ungual 

 ])halanx," &c. &c., to this day no foot has been found con- 

 taining a bone which resembles it ; no indubitable terminal 

 phalange resembles it closely ; while it is closely matched by 

 Dinosaurian dermal armour, es])ecially that of Scelidosaurus. 

 That it was a nasal horn is highly improbable ; but that it is 

 a dermal spine of some Dinosaur seems almost certain after a 

 comparison of the specimens. And if any one, thirty years 

 ago, had had the opportunities which students have now in 

 the national collection, I venture to think that Dr. Mantell's 

 lioni would never have been made to claw the dust. 



The bones of the metapodium of Aca7ithoj>koIis, placed toge- 

 ther, measure over their proximal ends 9 inches from side to 

 side, while the middle bone is about 6 inches long ; they are 

 well expanded at the proximal and distal ends ; and the shaft 

 becomes more slender from the first to the fourth. The 

 proximal ends of all are flattened, transversely truncated, and 

 slightly twisted outward ; while the distal ends are rounded 

 from above downward, and approximate to the usual pulley- 

 shaped articulation. The bones are all slightly worn, and 

 have suffered a little abrasion at their articular surfaces. 



The Jirst bone is short and strong. The flat jproxtmal arti- 

 culation is shaped in outline like half of a wide pear, with the 

 convex surface external, the vertical cut surface internal, and 



