ART. 16 



FOSSIL REPTILES FROM MONTANA — GILMORE 



13 



peciaily expanded. The diapophyses are short and stout, extending 

 outward at nearly right angles from the extreme lower side of the 

 arch. They have ovate, slightly cupped articular ends that look 

 downward and backward. 



Measurements of atlas and axis 



Mm. 



Greatest length of combined centra ^ 165 



Greatest length of atlas centrum (estimated) 88 



Greatest length of axis 77 



Greatest height of axis centrum 68 



Greatest height of atlas centrum 58 



Greatest length of first crevical rib 126 



Gervicals posterior to the axis. — In addition to the atlas and axis 

 there are three cervical vertebrae, one of which can be positively 

 identified as the third and the remaining two are provisionally re- 

 garded as the fifth and seventh respectively. The third, except for 

 its slightly increased size, has the proportions of the axis, as shown 

 in Figure 7. The cupped parapophysial facet has moved upward on 



FiGDEE 7. — Third cervical ver- 

 tebra OF Palaeoscincus ru- 

 gosidens. Type. No. 11868, 

 U.S.N.M. Lateral view. One- 

 third NATURAL SIZE 



Figure 8. — Fifth? cervical 



VERTEBRA OF PaLABOSCIN- 

 CUS RUGOSIDENS. TYPE. 



No. 11868, U.S.N.M. Lat- 

 eral VIEW. One-third 



NATURAL SIZE 



the median anterior border of the centrum and the diapophyses 

 have increased in length and general robustness. The top of the low 

 stout spine is somewhat expanded transversely. The centra of all 

 the cervicals are deeply amphicoelous. In the center of these cupped 

 ends, both front and back, are transversely elongated notochordal 

 projections that stand out prominently from the surrounding surface. 



