INTRODUCTION XV 



KZAEM Koenglisches Zoologisches und Anthropologisch-Ethnograph- 



isches Museum, Dresden 

 MCZ Museum of Comparative Zoology, Harvard University, 



Cambridge 

 MHNP Mus6um National d'Histoire Naturelle, Paris 

 MN Museu Nacional, Rio de Janeiro 



MP Museu Paulista (now Departamento de Zoologia, Secretaria 



da Agricultura, Sao Paulo) 

 MRHN Mus^e Royale d'Histoire Naturelle de Belgique, Brussels 

 MZUM Museum of Zoology, University of Michigan, Ann Arbor 

 NHMH Naturhistorisches Museum [Zoologisches Staatsinstitut und 



zoologisches Museum], Hamburg 

 NHMW Naturhistorisches Museums, Vienna 

 NMS Natur-Museum Senckenberg [Senckenbergische Naturfor- 



schende Gesellschaft], Frankfort-am-Main 

 NYZS New York Zoological Society, New York City 

 USNM United States National Museum 



UZMK Kobenhavns Universitet, Zoologisk Museum, Copenhagen 

 ZMB Zoologisches Museum, Berlin 



ZSBS Zoologische Sammlung des Bayerischen Staats [Zoologisches 



Staatssammlung], Munich 



Most of the colors named in the descriptions were compared with 

 those in the first edition of Ridgway's, "A Nomenclature of Colors 

 for Naturalists, and Compendium of Useful Knowledge for Ornitholo- 

 gists," 1886. 



The pen-and-ink illustrations for the text figures and most of the 

 profiles on the plates were made by me. 



The new species named by Dr. Adolpho Lutz between the years 

 1924 and 1929 were mostly without specified types. However, a 

 figure of each new species was painted under Dr. Lutz's direction, and 

 he referred constantly to it MT-hile making the notes accompanying the 

 published name. Whenever possible, I have designated as type the 

 specimen represented in one of these colored figures, now in the 

 possession of his daughter, Dr. Bertha Lutz. If I found no individual 

 corresponding to a colored figure, I designated as cotypes all the 

 specimens known to have been in his collections at the time his 

 published specific name first appeared. 



Where the number of specimens warranted, a graph comparing the 

 statistical variation of critical measurements in each species with all 

 in its group was prepared. These graphs, with an explanation of the 

 method of preparation, are found on pages 373-385. 



Every physical character found in frogs varies to some extent, 

 and some characters vary much more than others. These facts 

 have not been fully realized by some authors. For instance, the posi- 

 tion and development of the vomerine teeth, used by Boulenger, 

 Cope, and other herpetologists, are not constant in some species. 

 Key characters must therefore be interpreted rather widely, with 



