3°' 



E. C. CASE 



side of jugal, which at its lower end becomes sessile, and anteriorly 

 with the maxillary. It covers the anterior and the upper portion of 

 the outer process of the pterygoid. 



The bones of the facial region are very similar in position to those 

 of previously described specimens, but there is shown a separate bone 



at the anterior end of the 

 nasal, forming the pos- 

 terior wall and a portion 

 of the floor of the exter- 

 nal nares. This occupies 

 the same position as the 

 bone called the septo- 

 maxillary in Sphenodon 

 by Howes and Swinner- 

 ton.^ The bone has a 

 very peculiar form, being 

 bent at right angles so 

 that the anterior portion 

 forms the posterior half 

 of the floor of the nares, 

 and the posterior half 

 forms the posterior wall. The two bones of the opposite sides meet 

 in the median line, so that they would close the nares; but the inner 

 part of the posterior half is only one-half as high as the outer, so 

 that the inner opening of the nares is elevated. The air entering 

 the nares could not pass directly backward or downward, but first 

 rose over the half partition, and then down into the mouth. The 

 lower edge of the septo-maxillary joins the maxillary and premaxil- 

 lary. The suture between maxillary and septo-maxillary is marked 

 by two foramina. 



The section of the skull shows several peculiar conditions. There 

 are paired prevomers which are anteriorly united with the premaxil- 

 laries. Passing backward, they are convex upward, so that the 

 anterior portion of the mouth is vaulted. Opposite the maxillary- 



'^ G. B. Howes and H. H. Swinnerton, "On the Development of the Skeleton 

 of the Tuatera Sphenodon {Hatteria) pundatus," Transactions of the Zoological 

 Society of London, Vol. XVI (1903), Part I, No. i, pp. 1-87, Plates I-VI, Figs. 18. 



Fig. 4. — Posterior view of same skull. Letters 

 as in Fig. 2. 



