158 BULT.ETIIsr 154, UNITED STATES NATIONAL MUSEUM 



(Jadow (i'JUG, p. '>T'>) who. liowcNci'. saw vci'v few spcciiuens, con- 

 sidered melanostct litis a sinaUcr and nij^'i-escent i'onn closely allied to 

 tessellaUiH. 



It is surprising that \'an Denburgli (11)2^2, p. 532), after his years 

 of experience with western forms, should have written as follows : 

 "The t^'pes of meJanostethus were said to have been collected near 

 the Colorado River. They do not have the intense black throats of 

 many of the Arizonan specimens and it may be that they do not 

 belong to the form described above, but rather to C. tesseUatus tes- 

 sellatus. Cope's C. tesseUatus acthiops from Hermosillo, Sonora, is 

 based on specimens not distinguishable from those described above. 

 If further studies confirm these views, this name, C. aethiops 

 (Cope), will replace C. meJanostethus.'''' It wall be noted that Van 

 Denburgh admitted the uncertainty as to the classification of the 

 tj'pes of inelanostetlius., correctly indicating that they are inter- 

 mediate between the forms of tesseUatus wdth the darkest and light- 

 est lower surfaces, and yet with these intermediates and with nu- 

 merous others at hand, he was willing to overlook the fact of inter- 

 gradation and recognize the darker-ventralled variants as a distinct 

 species. It is true that aethiops is deep black below, as stated, but 

 nevertheless it appears that Cope (as opposed to Van Denburgh) 

 was entirely justified in describing it as a tentative subsjiecies, rather 

 than as a full species. 



The range of the most typical population of melanostetJiiis in the 

 United States is " The deserts of southern Arizona " as stated by 

 Stejneger and Barbour (1923, p. 72). Even here the young speci- 

 mens can scarcely be distinguished from those of the light phase of 

 many other regions. Specimens of intermediate size are usually 

 darker, and the adults of both sexes in the most " favorable " regions 

 almost always have deep blackish throats and often deep blackish 

 breasts as well. In rarer cases the entire under surface is dark 

 colored. Series usually show^ individual variation in regard to the 

 intensity and extent of the dark ventral suffusion, which is light 

 slate in some, but deep, shiny black in others. 



In the United States outside of Arizona, many specimens, typi- 

 cally -melanostethus.^ have been fonnd, but these have always been 

 reported as tesseUatus, due probably to their unexpected geograph- 

 ical position and the appearance of light-ventralled or intermediate 

 specimens Avith them. The specimens in question have been taken 

 as follows : 



CALIFORNIA.— Inyo County {Independence, M.V.Z.U.C.) ; San 

 Bernardino County {Needles, C. A. S.). 



IDAHO. — Ada County {Snake River, 8 mUes helow Swan FaUs, 

 M.V.Z.U.C). 



