APPENDIX. 
ART. XXXL — Principal Characters of American Jurassic 
Dinosaurs ; by Professor O. ©. Marsu. Part IIL With 
six plates. 
In the previous articles of this series, the writer has recorded 
the more important characters of several groups of Dinosaurs 
from the Jurassic deposits of the Rocky Mountain region.* In 
the present communication, some of the peculiar features in 
the structure of the Stegosauria are made known. This sub- 
order proves to be one of the most specialized of the known 
Dinosaurs, and differs widely from the other groups. 
Stegosaurus, Marsh, 1877. 
The type genus of this group (Stegosaurus) may be taken as 
the representative of the suborder. Among the characters 
which at present distinguish this genus from the other known 
toups of Dinosaurs are the following: 
(1) All the bones of the skeleton are solid. 
(2) The femur is without a third trochanter. 
(8) The crest on the outer condyle of the femur, which in 
Birds separates the heads of the tibia and fibula, is rudimentary 
or wanting. 
(4) The tibia is firmly codssified with the proximal tarsals. 
(5) The fibula has its larger extremity below. 
Various other important characters of the present group, 
Which are shared in part by some aberrant Dinosaurs, will be 
given below. : 
Tuer Skvuty anp Brain. 
The skull in the Stegosauria, so far as known, was remarka- 
bly small. In its main features it agreed more nearly with that 
of the genus Hatteria, from New Zealand, than with any other 
living reptile. The quadrates were fixed, and there was a 
quadrato-jugal arch, The jaws were short and massive. 
*This Journal, xiv, 613; xv, 241; xvi, 411; xvii, 86; and xviii, 501. 
Am. Jour. earn aad Serres, Vor, XIX, No. 111.—Manrcu, 1880. 
