136 E. B. BRANSON 



Captorhinus angusticeps, which has recently been referred to 

 Pariotichus by Broom. 1 In 1909 Williston described and figured 

 Pariotichus laticeps. 2 



Roof of skull. — No separation of the squamosal into two bones 

 was observed in either Pariotichus or the closely related genus 

 Labidosaurus. Williston first called attention to this in Labido- 

 saurus 3 and Broom shows no separation in his figures of Pariotichus. 4 

 ' A quadratojugal is present in its normal position in the temporal 

 region and this bone is also present in Labidosaurus. Its distinct- 

 ness is not apparent in the type specimen of Pariotichus laticeps 

 Williston, and was first noted in a specimen of Labidosaurus 

 recently acquired by Walker Geological Museum, and corroborated 

 by examination of other specimens. Dr. Case calls an element in 

 the base of the skull the quadratojugal, but it seems to be a part 

 of the squamosal. This part of the squamosal is indicated by the 

 numeral "2" in Fig. 3. In a specimen of Labidosaurus figured 

 by Williston, this part of the bone seems to be separate, but in 

 all other specimens examined there is no evidence of separation. 

 Dr. Williston worked over all of the skulls of Pariotichus and 

 Labidosaurus in the Walker Geological Museum to see if we agreed 

 •on this point and we are now in accord in saying that this is prob- 

 ably not a separate element. 



In 1883 in describing Pariotichus megalops, since referred to 

 Isodectes, Cope said: "At the extreme posterior angle is a very 

 small element in contact with the supraoccipital which may be 

 the true intercalare." 5 In 1896 he figured this bone in Pariotichus 

 aguti Cope, 6 and Case 7 and Broom 8 figure it in Pariotichus angus- 

 ticeps Cope. It is present in the form figured in this paper; and 

 in one or two other specimens of Pariotichus examined by the writer 



1 Bull. Am. Mus. Nat. Hist., XXVIII, 218. 



2 Biol. Bull., XVII, 241-55. 



3 Am. Jour. Anal., X (1910), 74. 



< Bull. Am. Mus. Nat. Hist,, XXVIII, 218. 



5 Proc. Am. Philos. Soc, XX, 630. 



6 Am. Naturalist, XXX, PI. VII. 



7 Bull. Am. Mus. Nat. Hist., XXVIII, 194. 



8 Ibid., XXVIII, 218. 



