REVISION OF THE KING SNAKES. 151 



more, tliat the homologues of the white or yellow rmgs may be 

 strongly suffused with red (confirming Cope's original description of 

 a specimen from Panama) , and that this red may extend across the 

 belly. The specimens at hand indicate that these rings may, on the 

 other hand, often be white or yellowish instead of red. 



The dental characters from a few specimens are as follows: Max- 

 illary teeth, 15 or 14, subequal, the last two or three only slightly 

 larger; mandibular teeth, 15, the anterior distinctly larger, decreas- 

 ing in size posteriorly; palatines, 10 to 12, more commonly 10, sub- 

 equal; pterygoids smaller than the latter, decreasing posteriorly, 17 

 to 19 in number. 



Habitat and habits. — ^Apparently nothing is recorded upon this 

 subject. 



Range. — ^This form is at present known only from Panama, and 

 from Colombia and Ecuador west of the Andes. In the latter coun- 

 try it has been taken at 4,200 feet elevation (Fowler, 1913, 168). Its 

 range meets that of polyzona in western Panama or southeastern 

 Costa Rica. If intergradation occurs it takes place in this region, 

 but two specimens from Panama and two from Costa Rica are nearly 

 typical of their respective forms. 



Published records for other localities than those listed are as follows : 

 Quito, Ecuador (Boulenger, 1880, 44); Cuenca, Ecuador (Peracca, 

 1897, 17); Vinces, Ecuador (P. acca, 1904, 13); Nanegal, Ecuador 

 (Despax, 1910, 370); Angelopolis, Colombia (Peracca, 1914, 96-111). 



Variation. — Since che specimens examined are nearly all from 

 Ecuador, nothing definite can be said about geographic variation. 

 Enough of individual variation is included in the description. 



Affinities. — On geographic grounds polyzona is the only form from 

 which microplwlis can be derived, but from the description it will 

 appear that it is very distinct from the latter in numerous structural 

 as well as color pattern characters. The differences between the two 

 are, however, only such as can be best explained on the assumption 

 of the above relationship. 



The most conspicuous changes, and how they may be accounted 

 for, are as follows: (1) The reduced number of temporals has re- 

 sulted from a reduction in size of the upper scute in each row and an 

 accompanying increase in the size of the lower plates; (2) the ventrals 

 have imdergone a slight decrease in number, a change often paralleled 

 by other forms in the genus; (3) the caudals have decreased dis- 

 tinctly, a change that is greater than but not different in kind from 

 that illustrated by other forms; (4) the paired caudals frequently fuse, 

 particularly near the tip of the tail; such fusion occurs sporadically 

 throughout the genus, but is more noticeable here than in any other 

 form; (5) the homologues of the yellow rings of polyzona, here more or 

 less red, have decreased in number, accompanying a decided increase 



