482 PROCEEDINGS OP THE NATIONAL BIUSEUM. vol.41. 



Viewed from above the posterior surface of the frontal is flattened 

 with the median part shghtly concave transversely. Forward of this 

 area the bone is convex in cross section, with a median ridge which 

 extends forward to the broken end of the bone (see fig. 1). The pos- 

 terior part of this edge is obtuse, but more anteriorly it has a sharp 

 edge. In front of the center, on either side of the ridge, the bone is 

 shallowly concave. The carinate condition of the frontal is also 

 found in Platycarpus and, to a less degree, in some of the other genera. 

 It is not present in Tylosaurus. The Dosterior border is nearly 



straight, with a 



slight median emar- 



^,p^-,-_^p<||jj^'|\ gination where it 



PWV li vliV ™^^^'S *'^^® parietal. 



A^W^\\l ' iv I ^ On either side o£the 



A "" \\\V p \ middle the borders 



i \*^^ l^n III Ml '""'^^ ^^^ broken so that 



/ ', \\\, i|i/, "r\ the exact outline of 



L I >.\ti Mm 4 this edge can not 



y^ ' \\ I'llnM/lf /;// / Vv ^® determined, al- 



A'' ^ ' MmlWl'^^ '^' \ thoughitapproaches 



/"'i ''^illR^^' \ *^® frontal of 



/ ^ * ^'ll' iPif/ i m Brachysaurus more 



/. >, ■-" * lb '1 9/^-^ ^ M iiearly than that of 



i\ \. --^'jW^ ^^/^ , .M any ^of the other 



wv, - ^~^^£^ ^ "^ ^ '^ ^ /.^^ / lateral mar- 



^^^^pi^._^^^^^ % ^^C^^^fii^^>^ gins are slightly un- 



^N^_^^^'' "=^-'^'^<^^ y dulatory and toward 



P the front are conver- 



FlG. 1.— Top VIEW OF FRONTAL OF GlOBIDENS ALABAMAENSIS. TYPE- gCUt. TllC pOStCrioT 

 SPECIMEN, i NATURAL SIZE, a, ANTERIOR END; O, POSTERIOR END. „! \ i\ • 



^ angle, where this 



bone meets the post-frontal, is thickened. The median lateral mar- 

 gin forming the upper border of the orbit is slightly emarginate and 

 obtusely rounded. 



Immediately in front of the free orbital margin begins the line of 

 union with the prefrontal. The entire pointed anterior part of this 

 bone is missing, as shown in figure 1 . 



On the under side are two wide, massive parallel ridges which 

 bound the cavity for the olfactory lobes. At the outer sides of these 

 ridges the bone is deeply excavated for sutural union with the pre- 

 frontals. 



Measurements of frontal. 



mm. 



Greatest vridth of frontal 160 



Greatest length of frontal 147 



Greatest width l:)etween orbital margins 112 



Greatest width olfactory cavity 24 



The greatest width of the frontal of Brachysaurus is also 160 mm. 



