202 



u. R. mii.i.i:k 



MYXOCYPRINUS 



ERIMY20N MOXOSTOMA CATOSTOMUS 



THOBURNIA \ PANTOSTEUS 



IcHASMISTES 

 'XYRAUCHEN 



' — AMYZON [MIOCENE, N AMJ 



hHYPOTHETICAL PHYLOGENY 



OF THE FAMILY 



CATOSTOMIDAE 



CVPRINIO ? PROTOTYPE 



Fig. 11. Hypothetical phylogeny of the Catostomidae. The approxi- 

 mate number of species in each subfamily and tribe is shown in the 

 circles. 



are from Miocene deposits in British Columbia, Nevada, and 

 Colorado, and arc placed in an extinct genus Amyzo7i. Superficially, 

 at least, this sucker bears a close resemblance to the living genus 

 Ictiobus, but a careful comparison with Myxocyprinus may show 

 Amyzon to be closer to that Old \\\jrld representative. Although the 

 fossil evidence is inconclusive, it seems probable that the Cato- 

 stomidae arose in southeastern Asia and soon crossed a Bering land 

 bridge to America, leaving a relict in China, and that in late Pleisto- 



Fig. 12. Humpback sucker, Xyraiichen tcxanus, an endemic genus of 

 the Colorado River s>'stem. (From original drawing by S. F. Denton 

 (nuchal hump retouched); see Jordan and Evermann, 1900, Fig. 88.) 



