Prof. O. C. Uarsh—Comparison of Dinosauria. 207 
All the known members of the group appear to have had an 
osseous dermal armour, more or less complete. 
One of the best preserved specimens of the Stegosauria in Kurope 
was described by Owen, in 1875, as Omosaurus armatus, and the 
type specimen is in the British Museum. It is from the Kim- 
meridge Clay (Upper Jurassic), of Swindon, England. The skull 
is wanting, but the more important parts of the skeleton are 
preserved. Various portions of the skeleton of several other 
individuals have also been found in England, but the skull and 
teeth still remain unknown. 
A recent examination of these specimens by the author disclosed 
no characters of sufficient importance to separate them from the 
genus Stegosaurus, and, as the name Omosaurus is preoccupied, they 
should, for the present, at least, be referred to Stegosaurus. The 
discovery of the skull and the dermal armour may not unlikely 
prove them to be distinct, but the parts now available for comparison 
do not alone authorize their separation. 
The type specimen of Anthodon serrarius, Owen, a fragment of 
a jaw from South Africa, and now in the British Museum, has teeth 
so very similar to the American forms of Stegosaurus, that, judging 
from these alone, it would naturally be referred to that genus. 
Hyleosaurus, Mantell, from the Wealden, has teeth of the same 
general type, but most of those referred to it, by Mantell and others, 
pertain to the Sauropoda. This genus, as well as Polacanthus, Hulke, 
from the same formation, Acanthopholis, Huxley, from the Cretaceous, 
and Scelidosaurus, Owen, from the Lias, are known from English 
specimens, but have not yet been found on the Continent. No 
American forms of these genera have yet been discovered. 
An interesting Cretaceous member of this group is the Struthio- 
saurus, Bunzel, 1871, apparently identical with Danubiosaurus of 
the same author, 1871, and Cratgomus, Seeley, 1881. It is from 
the Gosau formation of Austria. Although only fragments of the 
skeleton and dermal armour are known, some of these are very 
characteristic. One specimen of the latter, figured by Seeley, and 
regarded as a dermal plate, bearing a horn-like spine ‘“‘exactly like 
the horn-core of an ox,”1 is very similar in form to some proble- 
matical fossils from America, the exact horizon of which is in 
doubt.” 
Palgoscincus, Leidy, 1856, from the Cretaceous, and Priconodon of 
the author, 1888, from the Potomac formation, are, perhaps, allied 
forms of the Stegosauria, but, until additional remains are found, 
their exact affinities cannot be determined. Apparently, the oldest 
known member of this group in America is the Dystropheus, Cope, 
1877, from the Trias of Arizona. In Europe, none have yet been 
1 Quart. Journ. Geol. Soc. of London, vol. xxxvii. pl. xxviii. fig. 4, 1881. 
? Additional remains secured during the past season prove conclusively that some 
of these ‘‘horn-cores,’’ if not all, were attached to the skull in pairs, and one 
specimen found in place has since been described by the author as Ceratops montanus 
(Silliman’s Journal, vol. xxxvi. p. 477, December, 1888). It is from the Laramie 
formation of Montana. Others have been found in Colorado and in Wyoming. 
These are all much larger than the European specimens. 
