18 . 
Dinosauria — Omosaurus. 
The skull shows many points of resemblance to that of 
Iguanoclon , especially by the presence of a predentary bone, but- 
it is lower and narrower and in this respect it resembles the 
Scelidosaurian type. 
Fig. 20. — Left lateral view of skull of Stegosaurus staiops (Marsh), \ natural size ; from 
the Upper Jurassic, S. Colorado, North America, a, nares; b, orbit; c, infra- 
temporal fossa ; pm, premaxilla ; to, maxilla; u, nasal; pf, prefrontal; so, supra- 
orbital; fp, postfrontal; po. postorbital; /, lachrymal; j, jugal ; q, quadrate; sg, 
squamosal; oc, occipital condyle; ar , articular; sc i, surangular; an, angular; s, 
splenial ; d, dentary ; pd, predentary (after Marsh). 
To this sub-order are referred the remains of a large Dinosaur 
from the Ivimmeridge Clay of Swindon, Wilts, described by Sir 
Richard Owen in his Monograph on the Fossil Reptilia of the 
Mesozoic Formations (Palaeontograpliical Society’s Volume for 
Omosaurus. 1875), under the name of Omosaurus armatus. The series com- 
prises, in an immense block, the iliac bones of either side with 
the entire sacrum, retaining the normal form and position, an 
ischium, a femur, several dorsal and caudal vertebrae projecting 
in bold relief from the background of grey stone, forming a 
magnificent fossil group unique of its kind. 
In addition to the bones above mentioned (which are all 
imbedded in one block (V O'' x 7' 6"), a large dermal spine, 
several centra and processes of many vertebrae and chevron- 
bones, an entire humerus, ulna and radius with carpal and 
metacarpal bones, all parts of the same fore-limb ; also a com- 
plete ischium and pribis, and six caudal vertebrae, were found 
lying in the clay around the larger mass. 
The femur measures more than 4 feet, and the humerus 
is nearly 3 ft. in length and enormously broad. The head and 
neck are unfortunately wanting, but there is little doubt 
that nearly the entire animal might have been obtained had 
some competent person been present in the pit when the 
remains were first observed. 
4 
