0. C. Marsh — Dinosaurs of N. America. 41 



long and flexible, and was the lightest portion of the vertebral 

 column. The body was short, and the abdomen of moderate size. 

 The legs and feet were massive, and the bones of the limbs all 

 solid. The feet were plantigrade, and each footprint must have 

 covered about a square yard ! The tail was large, and nearly all 

 the bones were solid. The very small head and brain and the 

 slender neural cord, indicate a stupid, slow-moving reptile. The 

 beast was wholly without offensive or defensive weapons or dermal 

 armature. Barosauriis is an allied form. Of European forms 

 Ceiiosaurus longiis, from the Great Oolite, Oxford, Ornithopsis Hulkei, 

 from the Wealden of the Isle of Wight, have the skeleton con- 

 structed like Brontosaurus, with the same large cavities in the centra 

 of the vertebrae. The teeth named Hoplosaurus armatus, Gervais, 

 from the Wealden, Isle of Wight, are also identical in form with 

 those attributed to Brontosaurus excelsus, Marsh.' 



One of the most remarkable heads of any of this curious gi'oup 

 is that of Diplodociis, which, when seen in profile, forcibly recalls 

 the expression of the "Mock-turtle" by J. Tenniel, in "Alice in 

 "Wonderland." The orbits are large and placed far back in the 

 cranium; the facial portion is elongated and broadened in front; 

 the nasal opening is very large and placed near the apex of the 

 skull. The teeth, which are very weak, slender and cylindrical 

 in shape, resemble a row of bluntly-rounded pins ; they are all 

 crowded to the front of the jaws, 4 in each premaxillary and 3 in 

 each maxillary = 26 above, and 10 in each dentary of the lower 

 jaws = 46 in all. A section of the maxillary bone shows provision 

 for an abundant succession of new teeth when required, and from 

 their shallow insertion they would probably have been readily 

 detached. No restoration is given of Diplodociis save of the skull ; 

 but the beast was probably intermediate between Atlantosaurus and 

 Morosaurus in size, and from 40 to 50 feet in length. The teeth indi- 

 cate an herbivorous diet, the animal feeding largely upon succulent 

 vegetation, and the position of the nares seems to indicate an aquatic 

 mode of life. Morosaurus is placed near to Diplodociis. The limbs 

 suggest a plantigrade progression, as in Brontosaurus. There does not 

 appear to be any representative of Diplodociis out of North America. 



In the division named by Marsh the Predenta.ta, all the members 

 have a predentary bone (called by Hulke the presymphysial bone), 

 which is absent in all other dinosaurs, but is present in fishes of 

 the genera Aspidorliijnchus and BeJonostomiis. This order includes 

 the Stegosauria (or plated lizards), the Ceratopsia (or horned 

 lizards), and the Ornithopoda (or bird-footed dinosaurs). All these 

 are herbivorous foi'ras. 



Stegosaurus probably rivalled Brontosaurus and the other non- 

 plated dinosaurs in size : all its bones, however, were solid ; the 

 vertebrge were biconcave ; its body was defended by strong com- 

 pressed dorsal bony spines and plates, which in life were encased 

 in horny sheaths ; its head was very small in proportion to the size 

 of the entire animal, whilst its brain was only xio that of an 

 ^ Similar remains have been met witli in Madas'ascar and in Patagonia. 



