INTRODUCTION. XXll 
The other Catostomine have the dorsal fin short. Two of the genera are only found 
west of the Rocky Mountains, viz. Chasmistes (4 species) and Xyrauchen (2 species). 
One species of Xyrauchen is recorded from Northern Sonora. Catostomus comprises 
one species from Eastern Siberia and about twenty-five from North America, chiefly 
in the Rocky Mountain region. ‘Two species occur in Mexico, one from Sonora and 
one from the Rio Grande. Mo.xostoma includes twenty species from the United States 
east of the Rocky Mountains, from the Great Lakes to the Rio Grande; in Mexico 
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DIsTRIBUTION oF CATOSTOMIN A. 
one species is found in the Lerma System and another in the Rio Mascota, a small 
Pacific coast stream to the south of the Rio Grande de Santiago. Four monotypic 
genera allied to Moxostoma from the eastern part of the United States complete the 
count of the Catostomine. 
The Cyprininz comprise more than 1000 species from all parts of the world except 
the extreme north and the Neotropical and Australian regions. Less than 200 species 
are known from Africa, and most of these belong to Indian genera; they are absent 
from Madagascar. The Indian Region is the richest in genera and species and the 
most generalized types occur there ; fossil Cyprinide are found in Tertiary deposits of 
uncertain age in Sumatra, In the Palearctic Region the Cyprinine are an important 
