42 MEXICO AND CENTRAL AMERICA 
and of central Mexico fall between these extremes. In 
northern Mexico the stature increases considerably, 
average measurements for the Yaqui being in excess of 
5 feet 6 inches. ‘To make up for their lack of height 
the southern Indians are sturdy and heavy muscled, 
with deep chests. Their hair is usually black and 
straight, but occasionally wavy. Light beards and 
mustaches are sometimes worn, especially by the Mayas. 
The eyes are so dark brown as to appear black to the 
casual observer. ‘They are set rather wide apart and 
while usually horizontal they seem, in some instances, to 
have a slight Mongoloid tilt. Noses vary greatly but 
are often finely aquiline. The cephalic index (obtained 
by dividing the breadth of the head by its length and 
multiplying the result by 100) is rather high. The 
Mayas are strongly round-headed with an index of 85.0 
while their linguistic relatives, the Tzendals, have a 
medium index of 76.8. The other tribes of southern 
Mexico fall between these extremes. No long-headed 
peoples are found in this area although in northern 
Mexico some tribes approach the long-headed type. 
