58 



which also all the crocodilian and turtle remains were derived. Those from 

 the other deposit consist of portions of limb-bones, apparently of a single 

 individual of gigantic size. The more abundant fragments are referable to 

 three species. A fragment of a limb-bone is very similar to portions from 

 the other locality, and associated is a sacral vertebra of appropriate size and 

 characters. All of these were, therefore, referred provisionally to a single 

 species under the name of Agathaumas milo, but are here described under 

 Hadrosaurus occidentalis. The remaining specimens fall into two series. In 

 the one, the bones are occupied by a heavy mineral, and the surfaces covered 

 by a white layer, which is marked by irregular ridges, as though produced by 

 deposit along the lines of small adherent foreign bodies. In the other set, 

 the bones are lighter, more spongy, and not covered with the white layer ; 

 some of them are stained by the sesquioxide of iron Both present vertebrae 

 and limb-bones, which are related appropriately as to size and structure; that 

 is, the larger limb-bones have the same mineral character as the larger verte- 

 bra?, and the smaller as the smaller. These limb-bones represent correspond- 

 ing parts in the two, and, diffei'ing widely, confirm the belief in the. existence 

 of two species derived from the different types of vertebrae. In these fossils, 

 then, I see evidence for the existence of two species of two genera, which I 

 name — the larger, Polyonax mortuarius ; the smaller, Cionodon arctatus. 

 Both genera present a solid, cancellous filling of femora, tibiae, and other long 

 bones, and hence differ from such genera as Hadrosaurus, Hypsibema, Lcelaps, 

 and others. Cionodon differs in dentition from all Dinosauria where that part 

 of the structure is known; but it remains to compare Polyonax with Tro'udon 

 and' Palaoscincus of Leidy, which are known from the teeth only, while no 

 portions of dentil ion are preserved with the specimens at my disposal. 



< 'liar. gen. — Established primarily on a portion of the right maxillary 

 bone, with numerous teeth in place. The posterior portion exhibits a suture, 

 probably for union with the palatine bone, while the resl of the interior margin 

 is free. It is removed some distance from the tooth-line in consequence 

 of the horizontal expanse of the bone, while the outer face is vertical. 



The teeth are rod-like; the upper portion subcylindric in section, with 

 i he inner face flattened from apex to base, while the lower half is flattened by 

 an abrupt excavation to the middle, for the accommodation of the crown of 

 the successional tooth. The inner face of the tooth, from apex to base, is 

 shielded by n plate of enamel, which is somewhat elevated al tin- margins ; and 



