Page:Parasaurolophus walkeri, a new genus and species of trachodont dinosaur.pdf/14

10 lateral sutures (Plate V. Fig. 1) do not reach the extreme end, but terminate in or near two deep pits. The inferior of these pits is larger than the other and is situated a little more anteriorly. This pit is so deep that it can not be separated from its fellow of the opposite side by more than 25 mm. The superior pit is smaller and seems to pass through the terminal expansion as a sort of slit-like opening.

On the lateral aspect of the nasal, 170 mm. from the end, is a deep pit which is continued backwards as a narrow sulcus to the depression marking the anterior edge of the swollen extremity. Above and posterior to this pit is a well marked corrugated tuberosity 55 mm. in length. A similar but smaller tuberosity lies below the sulcus at this point.

A natural fracture crosses the crest 360 mm. from the end: this break has enabled us to ascertain the character of the cross section (Figs. 1 and 2). The crest is composed

apparently of four tubes of very thin bone not more than 5 mm. thick except at the superior and inferior points of junction. The lower line of junction, particularly, is considerably thickened and drawn down to a hatchet-like edge. The bones are coalesced as no sign of sutural union is visible.