ABT. 23. 



AN liXTINCT VARANID LIZARD GILMOEE. 



17 



Fig. 14. — Dorsal vertebra of Sa- 



NIWA ENSIDENS LEIDY. TYPE, CaT. 



No. 2185, U.S.N.M. Natural size. 



A VIEWED from left SIDE ; B, 

 VIEWED from posterior END ; nc, 



neural canal ; s, spinous proc- 

 ess ; t, TKANSVERSE PROCESS ; Z, 



anterior zygapophysis ; 2', pos- 

 terior ZYGAPOPHYSIS. 



having a slvuU of equal size, are considerably smaller throughout 

 the presacral series. The principal changes to be observed in the 

 structure of the vertebrae between the third and seventh are : First, 

 the development on the cervicals of forwardly projecting divergent 

 anterior zygapophyses, which become longer and heavier in each suc- 

 ceeding vertebra back to the sixth of 

 the series; second, the exogenous 

 process for the h3'pophyses, which is 

 largest on the axis, becomes rapidly 

 reduced in size posteriorly, until on 

 the sixth only a vestige® remains; 

 third, the small parapophyses first 

 developed on the third vertebra is 

 decidedly larger on the fourth and 

 increasingly so on each succeeding 

 vertebra. It would appear that the 

 fourth, fifth, and sixth vertebra bore 

 sliort ribs as in Hatteria, whereas in 

 Varanus salvator the seventh is the first to have a cervical rib; in 

 SauroTTialus the first rib is on the fourth cervical. 



The centra in this series are approximately the same length 

 throughout, with a cup in front and ball behind, a feature common 

 to most lizards, and which continues throughout the vertebral column. 

 The neural spines of the cervical series in 

 Saniwa are badly damaged, but they do not ap- 

 pear to have been taller than in the succeeding 

 dorsals, whereas in Varanus they are higher, and 

 wider fore and aft, than any that follow them in 

 the presacral series. These spines are thin trans- 

 versely, but wide (anteroposteriorly) plates of 

 bone that terminate dorsally with truncated ex- 

 tremities without transverse expansion. The 

 posterior zygapophyses do not protrude beyond 

 the ball of the centrum. 



The second series of four articulated vertebrae 

 (see pi. 2, fig. 2) are thought to represent 

 the eighth, ninth, tenth, and eleventh of the 

 vertebral series enumerated from the skull. These exhibit a flat- 

 tened ventral surface of the centra so typical of all the members 

 of the family Varanidae. The nonarticular surfaces of the centra 

 are slightly shorter than in the preceding series, as may be seen by 

 referring to the table of measurements. 



" In this feature Saniwa resembles Varanus griseus, where the hypophyses end with 

 the sixth cervical, there being only a slight elevation on the seventh, while in Y. salvator 

 hypophyses extend back to the seventh and sometimes a vestige is found on the eighth. 



Fig. 15. — Dorsal ver- 

 tebra of Saniwa 



HNS I DEN S LbIDY. 



Type, Cat. No. 2185, 

 U. S. N. M. Natural 

 SIZE. Superior view. 



t, TRANSVERSE PROC- 

 ESS ; Z, ANTERIOR ZYGA- 

 POPHYSIS ; «', POS- 

 TERIOR ZYGAPOPHYSIS ; 

 Zg, ZYGANTRA. 



