December 30, 1898.] 



SCIENCE. 



933 



generation has passed since any volume on 

 vertebrates was published, the last having 

 been ' a monograph on the structure and 

 development of the shoulder girdle,' by W. 

 K. Parker, issued for 1867. All the vol- 

 umes published since 1880 have been de- 

 voted to insects in the Linnrean sense. 



Mr. Boulenger has been ' for twenty-five 

 years a close student and collector of these 

 animals, which have always exercised an 

 extraordinary fascination ' on his mind and 

 he has utilized ' the enormous material 

 which had gradually accumulated in the 

 literature, [his] own notes, and the un- 

 rivalled collection in the British Museum.' 

 The outcome is worthy of the distinguished 

 author, and we have a monograph which 

 may serve as a model for other lands, and 

 not least for the United States. 



The first third of the work (p. 1-121) is 

 an 'introduction' to Amphibiology, treating 

 of the classification, external characters, in- 

 tegument, dermal secretion, skeleton, vis- 

 cera, habits, voice, pairing and oviposition, 

 spermatozoa, eggs, development and met- 

 amorphosis, tadpoles, hybrids, and geo- 

 graphical distribution. This introduction 

 is illustrated by forty-seven cuts and three 

 plates representing anatomical and physio- 

 logical data. A most useful feature is the 

 exhibition in dichotomous form of the ' ex- 

 ternal characters' (17), the ' osteological 

 characters' (44), 'the chief differences in 

 male uro-genital apparatus' (55), the am- 

 plexation or mode of embrace of the male 

 (69), the nuptial asperities (70), ' the prin- 

 cipal differences between the eggs' (79), 

 and the characteristics of the tadpoles 

 (105). 



The characters thus cleai'ly analyzed and 

 exhibited among the Anurans may be con- 

 sidered to have been coordinated, and the 

 resultant is a classification which expresses 

 quite nearly an equation for the collective 

 characters and is, therefore, a ' natural 

 classification.' So uniform are the external 



characters that not only are they no criteria 

 of the mutual affinities of the various forms, 

 but they are actually often misleading. The 

 early naturalists distinguished among the 

 phaneroglossate forms those with the up- 

 per jaw toothed or toothless and those with 

 toes having terminal disks contrasted with 



Sana esculenla. 



those without disks. Other characters were 

 found in the presence or absence of a ' tym- 

 panum' or ' ear' and^of ' parotoid glands' 

 as well as other less-used variations. It 

 became evident, however, that none of the 



