Page:Parasaurolophus walkeri, a new genus and species of trachodont dinosaur.pdf/11

Rh The left side of the head, which is exposed in the mount, has been sheared downwards, thus increasing its apparent depth: in the drawing (Plate IV) an attempt has been made to place the parts in proper relationship. In general the lower and lateral parts of the head conform to the usual trachodont arrangement, but the superior margin is truly extraordinary as it is continued backward in a gently convex line to a greater distance than the total length of the head proper.

This posterior prolongation or crest is a stout structure of considerable thickness and depth the details of which will be given later. It can scarcely be doubted that this crest is analogous to that of Saurolophus, but it is much more massive and directed less upwards than in that genus.

The general measurements of the head (I) are given below with those of Saurolophus osborni (II) for comparison.