364 



PROCEEDTXGS OF THE NATIONAL MUSEUM. 



Pacikic County, Washington. 



Scale formulas 17-19-17-15 

 17-15 



Museum 



No. 



Cal.Ac. Sci. 



29924 

 29923 

 29926 



Locality. 



Trap Creek 



do 



....do 



....do 



This set has markedly somber hues; the ground dark brown; 

 dorsal and lateral spots indicated by darker shades; median stripe 

 narrow, pale yellow; lateral stripe distinct; below dark grey. The 

 measurements of the largest specimen, No. 29923, are as follows: 

 Total length, 516 mm.; tail, 115; head, 17; snout, 4.8; eye, 2.6 mm. 



SUMMARY OF SCALE FORMULAE IN THAMNOPHIS ORDINOIDES. 



A tabulated summary of the occurrence of the different scale for- 

 mulae in these various sets will show at a glance the prevailing types 

 for each locality; to facilitate comparison they are given as per- 

 centages. 



This table brings out several instructive facts. The decrease in 

 the number of rows in specimens from more northern regions is not a 

 perfectly regular one, each locality having a decidedly different aver- 

 age. In the same locality there is never a single type. Where two 

 or more f omulas exist they are never equally divided among the speci- 

 mens, one type regularly predominating to a marked degree. 



