228 MEMOIRS OF THE CARNEGIE MUSEUM 
resented by a comparatively delicate roughened ridge, while the third has a promi- 
nent process which extends laterally and slightly back of the posterior face of the 
centrum. In the recent forms the transverse processes of the sacrum are more 
strongly developed, the first and second sacrals, especially, taking a more prominent 
part in the support of the ilium. In comparison with the heavy centra the neural 
canal is rather small, thus agreeing with what is observed in the Oligocene genus 
and differing from recent forms. ‘The neural spine of the first sacral is relatively 
smaller than in the recent dogs or cats, while that of the last sacral is much heavier, 
the spine on the median vertebra consisting only of a sharp low ridge, which uninter- 
ruptedly connects with the spines in front and behind. 
In Cynodesmus brachypus the sacrum is shorter and broader, the second sacral 
helps to support the ilium more prominently and the anterior neural spines were 
apparently proportionally more robust than in Daphanodon. The -spinous process 
on the last sacral in C. brachypus however, is, quite prominent, and is more com- 
pletely separated from the spine in front of it than in either Daphenodon or the 
recent dogs. 
MEASUREMENTS OF SACRUM. 
Antero-posterior diameter of centra... 
Greatest transverse diameter across the pleurapophyses.. 
Greatest transverse diameter at transverse processes Of last Sacral............ ccccesesssseeescreeseesseeneeee os 49 
Caudal Vertebrx. —The tail is very long and heavy; it has undergone practi- 
cally no change from that of the Oligocene form and is practically as well developed 
as in the lion or the tiger. The anterior face 
of the centrum of the first caudal is more con- 
vex and less depressed than the posterior. 
The transverse process is very heavy and pro- 
jects well backwards. The pre- and postzyga- 
pophyses have perfectly formed articular facets 
and are well expanded transversely. The 
neural canal is of moderately large size and 
oe SA SSF the spinous process is quite robust. 
Fig. 24. Caudal Vertebree of D. superbus. } The length of the centra of the succeeding 
nat. size. (1-28 indicate their respective posi- two caudals agrees with that of the first. The 
tions in the tail. ) 
transverse process on the second however, 
is, broader antero-posteriorly than in the first, but the neural spine is very much 
reduced, while on the third caudal the neural spine is represented only by a low 
ridge. The centrum of the fourth caudal is four or five millimeters longer than 
