146 



BULLETIN 114, UNITED STATES NATIONAL MUSEUM. 



The black tips on the red scales are exceedingly variable. Nearly 

 all individuals show them to some degree, but they are absent in a 

 few. The latter is true of a specimen from Chiapas and of another 

 from Guatemala. The black tips on the yellow scales are often 

 accompanied by a dark mottling of the rest of the scale. This is 

 rarely excessive. Occasional specimens show no black on the yellow 

 scales. Vera Cruz specimens show no approach to annulata, and the 

 relationship to nelsoni can not be told for lack of specimens. The 

 two examples from Costa Kica show no approach in black spotting 

 of the yellow rings to micropliolis. 



The narrowness and uniform width of the yellow wings characterizes 

 annulata and nelsoni as well as polyzona, and is probably evidence of 

 relationship. The two Costa Rican specimens both have these rings 





Fig. 45.— Map showing locality kecords for Lahpropeltis polyzona. 



very narrow. The transition to micropholis is shown by a specimen 

 from Panama and one from Darien, both of which have the yellow 

 rings wider than in polyzona but decidedly narrower than Ecuadorean 

 examples of micropliolis. These have the scales of the yellow rings 

 strongly black-tipped but less so than is typical of the latter form. 



Affinities. — That all the Mexican and Central American represen- 

 tatives of the triangulum group are closely related hardly needs 

 argument. It has not been doubted. The difficulty has lain in 

 correctly defining the several forms and determ.inmg just what the 

 relation o± each to each is. The evidence from variation and geo- 

 graphic probabilities is that polyzona is directly related to micropholis 

 and that it is distinct from annulata on the Gulf side of Mexico. The 

 nature of its relationship to nelsoni, on the Pacific side of Mexico, 

 must be learned at a future date. 



