SYSTEMATIC REVISION 21 



suture. A considerable part of its surface presents inferiorly. The supra- 

 mastoid lies between the supratemporal and the post frontoorbital. 



"The supraoccipital extends well forward on the superior face of the 

 cranium, the median suture equaling the length of the parietal bone. They 

 have an extraordinary transverse extent. The median suture of the parie- 

 tals is rather longer, and it is separated by the small parietal foramen at a 

 point one-third its length from the frontal suture. The posterior width of 

 the frontal is equal to three-fifths its length, and is a little greater than the 

 interorbital width. It extends as far anterior as posterior to the orbits. 

 The posterior suture is trilobate. The postfrontals are suboval with the 

 long diameter at 45° to the median line, and the anterointernal border 

 excavated by the orbit. They do not advance on the internal border of the 

 latter, resembling the prefrontals in this respect. The supramastoids are 

 necessarily well produced forwards to meet the short postfrontals, advanc- 

 ing far anterior to the posterior border of the jugals. 



"The premaxillaries are short and wide, and are widely truncate by the 

 frontal posteriorly. The prefrontals do not extend posteriorly to the 

 inner border of the orbit, but they join the jugal by a considerable suture. 

 The nasals occupy their usual position and are rather small; one of them 

 is fused with the premaxillary in the specimen. The maxillaries are small, 

 especially in the facial part, which does not reach the orbit. The jugal is a 

 relatively large bone and has an irregular posterior outline, where it joins 

 the quadratojugal and the supratemporal. 



"The great expansion of the roof bones posterior to the quadrate is asso- 

 ciated with a considerable expansion of the pterygoids in the same region. 

 The palatopterygoid arch has the relations prevalent in the Stegocephalia, 

 but (what is novel so far), its anterior and chiefly palatine portion carries 

 a single series of teeth on the external and anterior border, which is con- 

 centric with the premaxillo-maxillary series, as in Cryptobranchus. Poste- 

 rior to this is a pair of straight series of teeth, probably on the vomers, 

 which form an anteriorly directed right angle at the middle line. They do 

 not extend so far posteriorly as do the maxillary teeth, and the latter do 

 not extend so far posteriorly as the pterygopalatines which terminate at a 

 straight line drawn through the posterior borders of the orbits. The pos- 

 terior nostrils are situated between the two series of palatal teeth. The 

 external nostrils open forwards and outwards. Maxillary and premaxillary 

 teeth twenty-three on each side. Palatines, twenty-four; vomerines, ten. 



"The composition of the huge horns is thus the result of the fusion of the 

 three posterolateral roof elements into one, thus obliterating the notch which 

 separates the tabular from the quadratojugal bones in most other Stego- 

 cephalia." 



Revised description: 



1. Horns terminating more bluntly or with spatulate ends. Not 



curved in at ends. The posterior edge of the skull with a wide 

 concavity. 



2. Anterior edge of frontal nearly midway between orbits and 



nares. 



3. Vomerine teeth arranged as a wide V with the apex forward. 



4. Anterior edge of skull sharper. 



5. Sculpture of facial region not distinctly radial. 



6. Orbits smaller. 



