UKIVERSIT7 



PREFACE. 



To the zoologists into whose hands the present work may come, it 

 is deemed expedient to state, that as far as the families and genera are 

 concerned, the author does not profess to give a full synonymy thereof. 

 Indeed, it was first assumed that the earliest quotation would suffice, 

 and it is but subsequently that the most prominent sources have been 

 referred to. In regard to the species, all the synonyms that could be 

 found have been quoted. 



Litigious questions of nomenclature, concerning genera and species, 

 have been dealt with according to the principle of priority. In a single 

 instance, however, a species does appear under a name which, accord- 

 ing to that principle, ought to have been changed ; we refer to Oligo- 

 soma zelandicum (p. 246). That the subject has been under considera- 

 tion, is evinced by the synonymy accompanying it, where the name of 

 Oligosoma moco is quoted. Not possessing the dates at the time the 

 MS. was prepared, an oversight in proof-reading will account for the 

 want of conformity in the reference to the " Proceedings of the Aca- 

 demy of Natural Sciences of Philadelphia," in which a synopsis of 

 the new genera and species has been published, and where it was 

 anticipated also that the latter name would appear. 



The descriptions of several of the Batrachians, from the fact of 

 having been drawn up from specimens preserved in alcohol, may ill 

 compare with recent or living ones, especially such as were not sketched 

 from life. A protracted immersion in alcohol is apt to contract the 



