SKULL OF PTERANODON LONGICEPS Marsh. 7 



crest." An examination of small fragments retaining the natural curvature of this region 

 leads to the conclusion that the ridge was not so marked over the upper jaw as Pro- 

 fessor Marsh supposed. On the midline between the orbits, however, the beginning of 

 the upper border of the great sagittal crest is clearly to be seen. 



Side View of Skull. 



The side view of the skull is scarcely less instructive than the palatal view, as it 

 gives an excellent idea of the general proportions of this remarkable type. In front of 

 the large narial vacuity extends an almost unbroken arch of bone formed by the united 

 premaxillae, maxillae, and nasals. The outline of the superior border of the upper jaw 

 or snout is continued in a slightly ascending curved line above the narial vacuities 

 and orbits into the upper margin of the sagittal crest. In figuring this strange out- 

 growth from the parietal and supraoccipital bones, Professor Marsh gave an example of 

 his exceptional shrewdness in working from fragmentary material. As seen in Plate I, 

 figure 1, there remains only the basal portion of the great crest once borne by the type 

 skull. From the evidence offered by this, he was able to anticipate later discovery by 

 figuring and describing an enormous crest that formed about one-third of the entire 

 length of the skull. The only complete large crest known is that of a specimen identi- 

 fied with P. ingens. No. 2473 (Plate II, figure 2). Under that species, the form and func- 

 tion of this remarkable part of the skull will be further discussed. 



Beneath the antorbital vacuities, the maxillae are seen extending backward to meet 

 the supposed jugal elements that continue the cutting edges of the jaw almost to the 

 quadrates. From the middle of the jugal arises the flat bar of bone separating the ant- 

 orbital vacuity or nares from the orbit. In the type, the ossifications forming this bar, 

 supposedly lachrymal, prefrontal, and nasal, can not be distinguished from each other. 

 The orbit is bounded inferiorly by the jugal alone, which apparently united posteriorly 

 with the squamosal and postorbital or postfrontal to form the supratemporal arcade, no 

 demarcation being shown between the two last-named bones in any skull of the genus 

 in the Marsh Collection. 



The exact relations and extent of the squamosal remain a vexed problem. In the 

 type skull of P. longiceps, as well as in that of P. ingens, an unbroken tract of bone, 

 which may be the squamosal, arises from the paroccipital region and after participating 

 with the jugal and postorbital elements in the formation of the supratemporal arcade 

 extends forward and downward in a long splintlike process overlapping the inferior 

 border of the quadrate. This interpretation of the squamosal is slightly at variance with 

 the views of Professor Williston, 1 who regards the inferior outer part of the supratempo- 

 ral bar of Nyctosaurus as a quadrato-jugal articulating with the postorbital, jugal, squa- 

 mosal, and quadrate. In the types of P. longiceps and P. ingens, suture-like lines show 

 on the outer sides of the quadrates, and may possibly indicate the position of thin 

 quadrato-jugal plates. Such a hypothetical arrangement of the lateral temporal elements 

 has at least the merit of agreeing with the position of the corresponding bones in the 

 generalized Hatteria skull, and the extreme elongation of basisphenoid, jugal, and 

 quadrate in Pteranodon removes any possible lack of harmony in a proportionately long 

 squamosal. 



1 On the Skull of Nyctodactylus. 



Memoirs Conn. Acad., Vol. II. 2 



