48 
Foramina of Spinal Neryes.—All the neural arches 
except that of the atlas and usually about the last 5 are 
perforated by two foramina on each side for the exit of the 
spinal nerves (figs. 12, 14, 17, 18, 19). The ventral 
foramen is usually situated a little anterior to the dorsal 
one. Of the last 5 caudals the last is not perforated at 
all, and the preceding 4 have only one perforation on each 
side (fig. 19). The last vertebra, as of course in all the 
other caudals, has both a neural and a haemal canal. 
Zygapophyses. 
zygapophyses decline after about the 14th vertebra, and 
As shown in fig. 18, the anterior 
about the last 7 caudals have practically no zygapophyses 
at all. After the 15th the pre-zygapophysis is much re- 
duced, and only very slightly overlaps the vertebra in 
front or does not do so at all. Hence behind this vertebra 
the post-zygapophyses are entirely lacking. 
Strengthening Ridges.—These are disposed much the 
same as in the trunk vertebrae, except that in the hinder 
caudals there is a tendency for the ridges to be collected 
into one strong ridge situated mid-laterally on the 
centrum. This, however, does not obtain in all ihe pos- 
terior caudals (ep. fig. 19). 
Notochord.——AI1 the caudals have a notochordal canal 
except occasionally the last. The centra of the most pos- 
terior vertebre are always less ossified than those in front, 
and hence the notochordal spaces are larger. The urostyle 
is deeply excavated also, but the excavation extends 
straight backwards and does not turn up. 
Accessory Ribs.— The tubercles which have been 
identified as the remains of the accessory ribs are well 
marked on the anterior caudals, but diminish backwards 
and are practically absent on about the last 12. In the 
anterior caudals they occupy the position of the transverse’ 
processes of the trunk vertebre. 
