-40- 
RTLA Number 
XYZ 
Xenopus laevis 
1996 
Xiphophorus helleri 
2030 
Yellow rat snake 
1937 
Yellow sand mussel 
1902 
Yellowfin goby 
1897 
Yellowstone cutthroat trout 
1867 
Zebra-tailed lizard 
1849 
