BULLETIN" 199, UNITED STATES NATIONAL MUSEUM 



problem of distribution is more demanding of explanation than the 

 extreme dearth of Plethodontidae in the Guerrero "island" and in the 

 high western plateau, and the apparent replacement of that family in 

 the latter region, largely by the Ambystomidae. 



The treatment of forms in this volume differs little from that of the 

 two preceding volumes, except that the name of the collector of each 

 type is added. This name often is as important perhaps as the name 

 of the author of a species. Unfortunately, the collector is frequently 

 unknown or uncertain. This is true of the collections from Mexico 

 studied by Wiegmann, in which case we have given Deppe credit 

 for obtaining most of the reptiles. The other two men constituting 

 the collecting party, Count Von Sack and Schiede, were, we believe, 

 engaged primarily in the collection of orchids. However, it is not 

 at all improbable that some forms accredited to Deppe were actually 

 taken by one of the others. 



We refrain here from considering the implications that may be 

 deduced from a perusal of the combined data of the three volumes, 

 such as an investigation of faunal origins, lines of migration, relative 

 age of taxonomic groups, and faunal areas of ecological relationships. 

 However, we are fully aware that such consideration would doubtless 

 yield valuable information. 



The number of forms recognized in the herpetofauna of Mexico, 

 including those forms described since the fii'st of these checldists was 

 published, is relatively large. The following table represents the 

 numbers in the various groups: 



That there will in the future be considerable shifting of species to 

 the subspecific category, and changing forms we regard as subspecies 

 to the species category, is to be anticipated. On occasion we have 

 found even ourselves at variance on certain problems of this sort. 

 We both feel, however, that the currently and deservedly popular 

 trend toward recognition of subspecies where they exist has brought 



