10 BULLETIN 61, UNITED STATES NATIONAL MUSEUM. 



ber, consist of a double series of scutes about 49 to 134 in number 

 from the vent to the tip of the tail. 



Color. — The color pattern may be described in o;eneral as three 

 light stripes upon a darker ground, and, although there is consider- 

 able detail and variation in color, tliis description \d\\ be found to 

 hold in a general way for the genus. 



The ground color on the scales above the lateral stripe varies, as 

 a rule, from dark yellow at one extreme through the olives to black 

 at the other, and usually, when light enough to show it, exhibits 

 longitudinal rows of black spots. A^liere best developed {radix) 

 these spots are arranged in three longitudinal series on either side, 

 one below the lateral stripe and two above, the individual spots of 

 each series alternating with those of the adjacent rows. The 

 arrangement is not always so regular, however, for from this ideal 

 condition, so to speak, variations occur in various directions. In the 

 greater number of instances the spots of the first row are broken up 

 and do not form a definite series, while in many cases also the spots 

 of the second and third rows are interrupted by the ground color 

 along the keels of the scales. Frequently the spots of all three rows 

 tend to fuse with those of adjacent rows and form transverse bars or 

 blotches, and in one form (scalaris) this is the pattern throughout 

 the length of the body. Occasionally the spots retreat from the scales, 

 becoming reduced to narrow broken lines along the stripes, and in 

 one group (Sauritus) this is the characteristic pattern. In other 

 forms the scales between the spots are occasionally red. In all of 

 the forms exhibiting one of these styles of coloration the spots may 

 be entirely obscured by the darkening of the ground color, wliich 

 in some forms seems to be the typical condition. 



Wlien the skin is stretched the scales are drawn apart, and it is 

 seen that the lateral spots on the scales represent corresponding 

 series on the skin. Those beneath the first row are difficult to ob- 

 serve, as the skin is here apparently less distensible; they are evi- 

 dently, however, like their representatives on the first row of scales 

 in that they are more subject to irregularities, and are seldom to 

 be made out as a definite series. Above the lateral stripe the second 

 and third rows are usually distinct on the skin, whether or not the 

 spots on the scales are broken up or obscured by the ground color. 

 They also show a tendency to fuse, however, and this fusion may 

 either take place by the general fusion of the spots, leaving only 

 scattered light patches to indicate the interspaces; by transverse 

 fusion into bars; by the fusion of the upper row, which may involve 

 also part or all of the second row, the interspaces being limited to 

 the vicinity of the lateral stripe; or more rarely the two series fuse 

 as two longitudinal bands. 



