338 REPORT OF NATIONAL MUSEUM, 1898. 



C. IlIRGAX REGION. 



S. orcuitii Stejneger, S. vandcnhnrfjinyins Cope, S. hiseriatus Hallowell, S. zosteromus 

 Cope, (*?. hclii Van Denburgh. 



/. SONORAN REGION. 



S. clarkii Baird and Girard, S. couchii Baird and Girard, S. jarroviiCoiie, S. ornatiis 

 Baird, S. dugefiii Bocourt, S. minor Cope, S. microlepidoius Wiegniann, S. f/rammious 

 Wiegmann, S. scalaris Wiegniann. 



g. ST. LUCAS REGION. 



S. zosteromus Cope. 



II. Fauna Neotropica. 



a. central AMERICAN REGION. 



1. Tampican snbregion. 



S. varialnUn Wiegmann, S. nmeits Wiegmann, *S^. vivipartis Cope, S. lorqiiatva Baird 

 and Girard, S. serrifer Cope, S. microlepidoius Wiegmann, .S. (jrammicHS Wiegniann, 

 S. chri/sostictiis Cope, S. graciosiis Baird and Girard, S. spinosus Wiegmann. 



2. Coliman suhregion. 



S.utiformis Cope, S. jiyvrhocephalus Cope, S. melanorhinus Bocourt, S.horridiis Wieg- 

 mann, 8. siniferns Cope, S. microlepidotiis Wiegmann?, S. forquaius Greene and Peale? 

 S. keterolepis Bonlenger. 



3. Plateau of Guatemala. Guatemalan suliregion. 



S. malachiticiis Cope. 8. fiqiiamofius Bocourt, S. chrysosUctiis Cope, S. tanioenemis 

 Cope, »S^. lunoi Bocourt. 



4. Plateau of Costa Rica. Costa Rican suliregion. 

 iS'. malachitictis Cope, S. squamosiis Bocourt. 



In this tabic is shown a gradual transition of specific distribution from 

 the north to the south of the Central American region, some species 

 being common to two districts. The same is true of the regions of tlie 

 Nearctic realm, and were the divisions of the latter determined by the 

 species of Sceloporus they would have no greater value than those of 

 the Central American region of the Neotropical. They are, however, 

 distinguished by differences in the distribution of other types of ani- 

 mals, and are of much greater significance than the divisions of tlie 

 Central American region. 



Several species of the genus inhabit the adjacent areas of both 

 Faunae. Thus 8. grammicus and S. microlepidoius occur in both the 

 Tierra Teniplada (i?. nearctica) and Tierra Caliente {R. neotropica) of Mex- 

 ico. The »S'. variabilis and S. torqiiatus extend from the eastern Tierra 

 Caliente a short distance into Texas, and these species should perhaps 

 be omitted from our fauna. The *S'. spinosus appears to be a full member 

 of both of the great Fauna?, extending from tlie State of Puebla as far 

 as Florida. The distribution of the *S'. (jraciosus is still more anomalous. 

 It belongs to the central desert region of the F. nearctica as far north 

 as Oregon, but I have seen specimens which I can not distinguish from 

 it from near Jalapa, which is well south in the Tierra Templada of 

 Vera Cruz. The proper geographical location of the 8. thaycrii Baird 

 and Girard and 8. heterolepis Boulenger is yet uncertain. 



