ON THE SKULL OF NYCTODACTYLUS 53 I 



sions of the cirri are plainly present. Other impressions of 

 phyllopods or ostracods are also abundant in the matrix. 



S. W. Williston. 

 University of Kansas, 

 Lawrence, April, 1902. 



EXPLANATION OF PLATES. 



Plate I. Under surface of posterior part of skull, lying in the matrix 

 slightly enlarged. Near the anterior end are seen the two hyoid bones, and 

 in the occipital region, the small, triangular proatlas. 



Plate II. Fig. 1, Under view of skull ; Fig. 2, upper view of same, both 

 a little more than half natural size ; bo, basi-occipital ; efi t ectopterygoid ; fr, 

 frontal; ifiv, interpterygoid vacuity; itv, infratemporal vacuity; j, jugal ; /, 

 lachrymal ; mx, maxilla ; na, nares ; nas, nasal ; oc, occipital condyle ; pa, 

 parietal ; pal, palatine ; pf, prefrontal ; pof, postfrontal ; ppv, posterior pala- 

 tine vacuity ; px, premaxillary ; q, quadrate ; qj, quadrato-jugal ; sq, squa- 

 mosal ; z, pterygo-jugal vacuity. 



