REVISION OF THE KING SNAKES. 



77 



then reliance should be placed on the totality of characters. Adult 

 specimens which show no basal shading of the scales of the white 

 rings can be only hoylii. If basal shading is present, hoylii may be 

 distinguished from conjuncta by the fact that the infralabicils are 

 usually 9 instead of 10, the frontal plate has usually a right or obtuse 

 posterior angle instead of an acute one, and its outline is distinctly 

 pentagonal instead of nearly trigonal. However, too much reliance 

 should not be placed upon these last two characters. If the number 

 of ventral plates is well above the average for yumensis and conjuncta, 

 the specimen is apt to be a hoylii. Adult examples of hoylii may 

 resemble yumensis, but if the head is much spotted posteriorly and 

 particularly if the white bars across the prefrontals are strongly 

 convex behind and occupy more than half their area, it is a hoylii. 

 The accompanying table should prove useful in placing doubtful 

 examples, but since the distribution of these forms is fairly well known, 

 specimens may, with safety, be referred to their proper form by 

 locality only. 



Table of comparisons. 



Character. 



Yumensis. 



Boylii. 



Conjuncta. 



Infralabials 



Frontal 



Posterior angle 



Postero-lateral angle . 



White rings: 



Adults 



Young 



Head: Parietals, frontals, 

 supraoculars, second 

 and third rows of temp- 

 orals: Adults and young 



White bars on prefrontals: 

 Adults and young. 



Usually9 



Pentagonal. 



Right or obtuse 



Obtuse 



White scales always 

 dark brown at base. 



Usually like adults 



White spots very re- 

 stricted or absent. 



Usually simple bars oc- 

 cupying less than half 

 the area of the scute. 



Usually 9 



Pentagonal 



Right or obtuse 



Obtuse 



White scales only oc- 

 casionally dark brown 

 at base. 



No basal shading of 

 white scales. 



Usually like yumensis, 

 except in southern 

 California and north- 

 ern lower California, 

 where it is usually like 

 conjuncta. 



Usually rounded or an- 

 gular posteriorly, and 

 occupying more than 

 half the area of the 

 scute. 



Usually 10. 



More nearly trigonal. 



Usually distinctively 

 acute. 



Nearly or quite 180 de- 

 grees. 



White scales always dark 

 brown at base. 



No basal shading of white 



scales. 

 Numerous white spots or 



marks on these plates. 



Like boylii. 



Hahitat and TiaUts. — ^Although this form has been known since 1853 

 there is very little recorded about its habits and habitat preferences. 

 Townsend (1887, 239) refers to it as ^'not uncommon on the Lower 

 McCloud, in damp places near the river." Hailowell (1859, 14) says 

 of it, ''found in valleys and open prairies, very abundant, often 

 killed by travelers, and found lying on the roadside.'^ A specimen 

 from Marin County, California, bears the note "hj roadside in shade." 

 Merriam reports it (Stejneger, 1893, 204) as follows: ''Found in the 

 valley of the Lower Muddy near an abandoned mill at Overton, 

 Nevada, where several were secured in dense thickets of Atriplex 

 torreyi. About dark they began to emerge from these retreats. 



